From f08315c92b492ffd482932bbd4ce79c2c12a501a Mon Sep 17 00:00:00 2001
From: Stefan Ossendorf <stefan.ossendorf@googlemail.com>
Date: Sat, 8 Mar 2025 21:52:19 +0100
Subject: [PATCH 1/3] Csla.Analyzers.Extensions nullable aware #1233

---
 .../Csla.Analyzers/Csla.Analyzers.csproj      |  2 ++
 .../Extensions/ITypeSymbolExtensions.cs       | 24 +++++++++----------
 .../Extensions/SyntaxNodeExtensions.cs        | 10 ++++----
 3 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/Source/Csla.Analyzers/Csla.Analyzers/Csla.Analyzers.csproj b/Source/Csla.Analyzers/Csla.Analyzers/Csla.Analyzers.csproj
index 6d7e36ce3a..d4dc04d472 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/Csla.Analyzers.csproj
+++ b/Source/Csla.Analyzers/Csla.Analyzers/Csla.Analyzers.csproj
@@ -9,6 +9,8 @@
     <BaseOutputPath>..\..\..\Bin</BaseOutputPath>
     <EnforceExtendedAnalyzerRules>true</EnforceExtendedAnalyzerRules>
     <IsRoslynComponent>true</IsRoslynComponent>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>nullable</WarningsAsErrors>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/Extensions/ITypeSymbolExtensions.cs b/Source/Csla.Analyzers/Csla.Analyzers/Extensions/ITypeSymbolExtensions.cs
index b664bbc913..47ba2d1cee 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/Extensions/ITypeSymbolExtensions.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/Extensions/ITypeSymbolExtensions.cs
@@ -7,7 +7,7 @@ internal static class ITypeSymbolExtensions
     private static readonly Type[] SerializableTypesByMobileFormatter =
       [typeof(TimeSpan), typeof(DateTimeOffset), typeof(byte[]), typeof(byte[][]), typeof(char[]), typeof(Guid), typeof(List<int>)];
 
-    internal static bool IsBusinessRule(this ITypeSymbol @this)
+    internal static bool IsBusinessRule(this ITypeSymbol? @this)
     {
       return @this != null &&
         (((@this.Name == CslaMemberConstants.Types.IBusinessRule || @this.Name == CslaMemberConstants.Types.IBusinessRuleAsync) &&
@@ -15,7 +15,7 @@ internal static bool IsBusinessRule(this ITypeSymbol @this)
           (@this.BaseType.IsBusinessRule() || @this.Interfaces.Any(_ => _.IsBusinessRule())));
     }
 
-    internal static bool IsObjectFactory(this ITypeSymbol @this)
+    internal static bool IsObjectFactory(this ITypeSymbol? @this)
     {
       return @this != null &&
         ((@this.Name == CslaMemberConstants.Types.ObjectFactory &&
@@ -23,7 +23,7 @@ internal static bool IsObjectFactory(this ITypeSymbol @this)
           @this.BaseType.IsObjectFactory());
     }
 
-    internal static bool IsBusinessBase(this ITypeSymbol @this)
+    internal static bool IsBusinessBase(this ITypeSymbol? @this)
     {
       return @this != null &&
         ((@this.Name == CslaMemberConstants.Types.BusinessBase &&
@@ -31,7 +31,7 @@ internal static bool IsBusinessBase(this ITypeSymbol @this)
           @this.BaseType.IsBusinessBase());
     }
 
-    internal static bool IsInjectable(this ITypeSymbol @this)
+    internal static bool IsInjectable(this ITypeSymbol? @this)
     {
       return @this != null &&
         ((@this.Name == CslaMemberConstants.Types.InjectAttribute &&
@@ -39,7 +39,7 @@ internal static bool IsInjectable(this ITypeSymbol @this)
           @this.BaseType.IsInjectable());
     }
 
-    internal static bool IsDataPortalOperationAttribute(this ITypeSymbol @this)
+    internal static bool IsDataPortalOperationAttribute(this ITypeSymbol? @this)
     {
       return @this != null &&
         ((@this.Name == CslaMemberConstants.Types.DataPortalOperationAttribute &&
@@ -47,7 +47,7 @@ internal static bool IsDataPortalOperationAttribute(this ITypeSymbol @this)
           @this.BaseType.IsDataPortalOperationAttribute());
     }
 
-    internal static bool IsDataPortalRootOperationAttribute(this ITypeSymbol @this)
+    internal static bool IsDataPortalRootOperationAttribute(this ITypeSymbol? @this)
     {
       return @this != null &&
         ((@this.Name == CslaMemberConstants.Types.DataPortalRootOperationAttribute &&
@@ -55,7 +55,7 @@ internal static bool IsDataPortalRootOperationAttribute(this ITypeSymbol @this)
           @this.BaseType.IsDataPortalRootOperationAttribute());
     }
 
-    internal static bool IsDataPortalChildOperationAttribute(this ITypeSymbol @this)
+    internal static bool IsDataPortalChildOperationAttribute(this ITypeSymbol? @this)
     {
       return @this != null &&
         ((@this.Name == CslaMemberConstants.Types.DataPortalChildOperationAttribute &&
@@ -114,7 +114,7 @@ internal static bool IsSpecialTypeSerializable(this ITypeSymbol @this)
         specialType == SpecialType.System_DateTime;
     }
 
-    internal static bool IsIPropertyInfo(this ITypeSymbol @this)
+    internal static bool IsIPropertyInfo(this ITypeSymbol? @this)
     {
       return @this != null &&
         ((@this.Name == CslaMemberConstants.Types.IPropertyInfo &&
@@ -122,7 +122,7 @@ internal static bool IsIPropertyInfo(this ITypeSymbol @this)
           @this.BaseType.IsIPropertyInfo() || @this.Interfaces.Any(_ => _.IsIPropertyInfo()));
     }
 
-    internal static bool IsEditableStereotype(this ITypeSymbol @this)
+    internal static bool IsEditableStereotype(this ITypeSymbol? @this)
     {
       return @this != null &&
         (((@this.Name == CslaMemberConstants.Types.BusinessBase ||
@@ -133,7 +133,7 @@ internal static bool IsEditableStereotype(this ITypeSymbol @this)
           @this.BaseType.IsEditableStereotype());
     }
 
-    internal static bool IsStereotype(this ITypeSymbol @this)
+    internal static bool IsStereotype(this ITypeSymbol? @this)
     {
       return @this != null &&
         (((@this.Name == CslaMemberConstants.Types.IBusinessObject ||
@@ -142,7 +142,7 @@ internal static bool IsStereotype(this ITypeSymbol @this)
           (@this.BaseType.IsStereotype() || @this.Interfaces.Any(_ => _.IsStereotype())));
     }
 
-    internal static bool IsMobileObject(this ITypeSymbol @this)
+    internal static bool IsMobileObject(this ITypeSymbol? @this)
     {
       return @this != null &&
         ((@this.Name == CslaMemberConstants.Types.IMobileObject &&
@@ -150,7 +150,7 @@ internal static bool IsMobileObject(this ITypeSymbol @this)
           (@this.BaseType.IsMobileObject() || @this.Interfaces.Any(_ => _.IsMobileObject())));
     }
 
-    internal static bool IsObjectAuthorizationRulesAttribute(this ITypeSymbol @this)
+    internal static bool IsObjectAuthorizationRulesAttribute(this ITypeSymbol? @this)
     {
       return @this != null &&
         ((@this.Name == CslaMemberConstants.Types.ObjectAuthorizationRulesAttribute &&
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/Extensions/SyntaxNodeExtensions.cs b/Source/Csla.Analyzers/Csla.Analyzers/Extensions/SyntaxNodeExtensions.cs
index e1d9372f55..cb64b62820 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/Extensions/SyntaxNodeExtensions.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/Extensions/SyntaxNodeExtensions.cs
@@ -6,18 +6,16 @@ namespace Csla.Analyzers.Extensions
 {
   internal static class SyntaxNodeExtensions
   {
-    internal static bool HasUsing(this SyntaxNode @this, string qualifiedName)
+    internal static bool HasUsing(this SyntaxNode? @this, string qualifiedName)
     {
       if (@this == null)
       {
         return false;
       }
 
-      if (@this.IsKind(SyntaxKind.UsingDirective))
+      if (@this.IsKind(SyntaxKind.UsingDirective) && @this is UsingDirectiveSyntax usingNode)
       {
-        var usingNode = @this as UsingDirectiveSyntax;
-
-        if (usingNode.Name.ToFullString() == qualifiedName)
+        if (usingNode.Name?.ToFullString() == qualifiedName)
         {
           return true;
         }
@@ -26,7 +24,7 @@ internal static bool HasUsing(this SyntaxNode @this, string qualifiedName)
       return @this.ChildNodes().Any(_ => _.HasUsing(qualifiedName));
     }
 
-    internal static T FindParent<T>(this SyntaxNode @this)
+    internal static T? FindParent<T>(this SyntaxNode @this)
       where T : SyntaxNode
     {
       var parentNode = @this.Parent;

From 71c814c13e18e615eaa0a7828e6097bdbd7dc7a2 Mon Sep 17 00:00:00 2001
From: Stefan Ossendorf <stefan.ossendorf@googlemail.com>
Date: Sat, 8 Mar 2025 21:56:17 +0100
Subject: [PATCH 2/3] Csla.Analyzers.ManagedBackingFieldUsesNameof nullable
 aware #1233

---
 ...EvaluateManagedBackingFieldsNameofAnalyzer.cs |  2 +-
 .../EvaluateManagedBackingFieldsNameofCodeFix.cs | 16 +++++++++++++++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/Source/Csla.Analyzers/Csla.Analyzers/ManagedBackingFieldUsesNameof/EvaluateManagedBackingFieldsNameofAnalyzer.cs b/Source/Csla.Analyzers/Csla.Analyzers/ManagedBackingFieldUsesNameof/EvaluateManagedBackingFieldsNameofAnalyzer.cs
index 78a8c6d94d..2dfbd6a471 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/ManagedBackingFieldUsesNameof/EvaluateManagedBackingFieldsNameofAnalyzer.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/ManagedBackingFieldUsesNameof/EvaluateManagedBackingFieldsNameofAnalyzer.cs
@@ -51,7 +51,7 @@ private static void AnalyzeInvocationExpression(SyntaxNodeAnalysisContext contex
         {
           context.CancellationToken.ThrowIfCancellationRequested();
 
-          if (context.SemanticModel.GetDeclaredSymbol(variable) is IFieldSymbol fieldSymbol && variable.Initializer.Value is InvocationExpressionSyntax invocation)
+          if (context.SemanticModel.GetDeclaredSymbol(variable) is IFieldSymbol fieldSymbol && variable.Initializer?.Value is InvocationExpressionSyntax invocation)
           {
             if (fieldSymbol.Type.IsIPropertyInfo() && invocation.Expression is GenericNameSyntax invocationName)
             {
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/ManagedBackingFieldUsesNameof/EvaluateManagedBackingFieldsNameofCodeFix.cs b/Source/Csla.Analyzers/Csla.Analyzers/ManagedBackingFieldUsesNameof/EvaluateManagedBackingFieldsNameofCodeFix.cs
index 880c05d234..d9fb6b99cf 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/ManagedBackingFieldUsesNameof/EvaluateManagedBackingFieldsNameofCodeFix.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/ManagedBackingFieldUsesNameof/EvaluateManagedBackingFieldsNameofCodeFix.cs
@@ -34,10 +34,19 @@ public sealed class EvaluateManagedBackingFieldsNameofCodeFix
     public override async Task RegisterCodeFixesAsync(CodeFixContext context)
     {
       var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
+      if (root is null)
+      {
+        return;
+      }
       var diagnostic = context.Diagnostics.First();
       var diagnosticSpan = diagnostic.Location.SourceSpan;
 
-      var argumentSyntax = root.FindToken(diagnosticSpan.Start).Parent.AncestorsAndSelf().OfType<ArgumentSyntax>().First();
+      var parentToken = root.FindToken(diagnosticSpan.Start).Parent;
+      if (parentToken is null)
+      {
+        return;
+      }
+      var argumentSyntax = parentToken.AncestorsAndSelf().OfType<ArgumentSyntax>().First();
 
       context.RegisterCodeFix(
         CodeAction.Create(
@@ -58,6 +67,11 @@ private async Task<Document> UseNameofAsync(Document document, ArgumentSyntax ar
       var nameofExpression = SyntaxFactory.ParseExpression($"nameof({propertyName})");
 
       var root = await document.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
+      if (root is null)
+      {
+        return document;
+      }
+
       var newRoot = root.ReplaceNode(argumentSyntax.Expression, nameofExpression);
 
       return document.WithSyntaxRoot(newRoot);

From 4d94583f8e188e02c9febd29072d1c80a637b1b0 Mon Sep 17 00:00:00 2001
From: Stefan Ossendorf <stefan.ossendorf@googlemail.com>
Date: Mon, 10 Mar 2025 22:28:14 +0100
Subject: [PATCH 3/3] Csla.Analyzers nullable aware #1233

---
 ...sRuleInheritingFromBusinessRuleAnalyzer.cs |  5 ++
 ...essRuleChangeToBusinessRuleAsyncCodeFix.cs | 24 +++++++--
 ...leDoesNotUseAddMethodsOnContextAnalyzer.cs |  4 ++
 .../CheckConstructorsAnalyzer.cs              |  6 +--
 ...ructorsAnalyzerPublicConstructorCodeFix.cs | 19 +++++--
 .../Csla.Analyzers/Csla.Analyzers.csproj      |  4 ++
 .../DoesChildOperationHaveRunLocalAnalyzer.cs |  5 ++
 ...ationHaveRunLocalRemoveAttributeCodeFix.cs | 24 ++++++++-
 ...erationHaveAttributeAddAttributeCodeFix.cs |  8 +++
 .../DoesOperationHaveAttributeAnalyzer.cs     |  4 ++
 .../EvaluateManagedBackingFieldsAnalyzer.cs   | 15 ++----
 .../EvaluateManagedBackingFieldsCodeFix.cs    |  4 ++
 .../EvaluateManagedBackingFieldsWalker.cs     |  6 ++-
 ...EvaluateOperationAttributeUsageAnalyzer.cs | 13 +++--
 ...EvaluatePropertiesForSimplicityAnalyzer.cs | 33 ++++++++----
 .../Extensions/ITypeSymbolExtensions.cs       | 29 +++++-----
 .../FindGetOrReadInvocationsWalker.cs         |  7 ++-
 ...rectReturnTypeResolveCorrectTypeCodeFix.cs | 25 ++++++---
 ...rationsWithIncorrectReturnTypesAnalyzer.cs |  4 ++
 ...onsWithNonSerializableArgumentsAnalyzer.cs |  4 ++
 ...RefAndOutParametersInOperationsAnalyzer.cs |  7 ++-
 .../FindSaveAssignmentIssueAnalyzer.cs        |  8 ++-
 ...gnmentIssueAnalyzerAddAssignmentCodeFix.cs | 11 +++-
 ...tIssueAnalyzerAddAsyncAssignmentCodeFix.cs | 54 +++++++++++--------
 .../FindSetOrLoadInvocationsWalker.cs         |  7 ++-
 ...alledInAsynchronousBusinessRuleAnalyzer.cs |  4 ++
 ...ynchronousBusinessRuleRemoveCallCodeFix.cs | 29 ++++++++--
 .../IsOperationMethodPublicAnalyzer.cs        |  6 ++-
 ...erationMethodPublicMakeNonPublicCodeFix.cs |  8 +++
 ...jectAuthorizationRulesAttributeAnalyzer.cs |  4 ++
 30 files changed, 276 insertions(+), 105 deletions(-)

diff --git a/Source/Csla.Analyzers/Csla.Analyzers/AsynchronousBusinessRuleInheritingFromBusinessRuleAnalyzer.cs b/Source/Csla.Analyzers/Csla.Analyzers/AsynchronousBusinessRuleInheritingFromBusinessRuleAnalyzer.cs
index 80fd67b3f7..7c3c7d5130 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/AsynchronousBusinessRuleInheritingFromBusinessRuleAnalyzer.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/AsynchronousBusinessRuleInheritingFromBusinessRuleAnalyzer.cs
@@ -47,6 +47,11 @@ private static void AnalyzeMethodDeclaration(SyntaxNodeAnalysisContext context)
       if (!methodNode.ContainsDiagnostics)
       {
         var methodSymbol = context.SemanticModel.GetDeclaredSymbol(methodNode);
+        if (methodSymbol is null)
+        {
+          return;
+        }
+
         var typeSymbol = methodSymbol.ContainingType;
 
         if(typeSymbol.IsBusinessRule() && methodSymbol.Name == "Execute" && methodSymbol.IsAsync)
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/AsynchronousBusinessRuleInheritingFromBusinessRuleChangeToBusinessRuleAsyncCodeFix.cs b/Source/Csla.Analyzers/Csla.Analyzers/AsynchronousBusinessRuleInheritingFromBusinessRuleChangeToBusinessRuleAsyncCodeFix.cs
index 44546c45e9..32a1ded619 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/AsynchronousBusinessRuleInheritingFromBusinessRuleChangeToBusinessRuleAsyncCodeFix.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/AsynchronousBusinessRuleInheritingFromBusinessRuleChangeToBusinessRuleAsyncCodeFix.cs
@@ -36,21 +36,31 @@ public sealed class AsynchronousBusinessRuleInheritingFromBusinessRuleChangeToBu
     public override async Task RegisterCodeFixesAsync(CodeFixContext context)
     {
       var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
-
+      if (root is null)
+      {
+        return;
+      }
       context.CancellationToken.ThrowIfCancellationRequested();
 
       var diagnostic = context.Diagnostics.First();
       var methodNode = root.FindNode(diagnostic.Location.SourceSpan) as MethodDeclarationSyntax;
+      if (methodNode is null)
+      {
+        return;
+      }
 
       context.CancellationToken.ThrowIfCancellationRequested();
       await AddCodeFixAsync(context, root, diagnostic, methodNode);
     }
 
-    private static async Task AddCodeFixAsync(CodeFixContext context, SyntaxNode root,
-      Diagnostic diagnostic, MethodDeclarationSyntax methodNode)
+    private static async Task AddCodeFixAsync(CodeFixContext context, SyntaxNode root, Diagnostic diagnostic, MethodDeclarationSyntax methodNode)
     {
       var model = await context.Document.GetSemanticModelAsync(context.CancellationToken);
       var methodSymbol = model.GetDeclaredSymbol(methodNode);
+      if (methodSymbol is null)
+      {
+        return;
+      }
       var typeSymbol = methodSymbol.ContainingType;
 
       var newRoot = root;
@@ -91,13 +101,17 @@ private static async Task AddCodeFixAsync(CodeFixContext context, SyntaxNode roo
           AsynchronousBusinessRuleInheritingFromBusinessRuleChangeToBusinessRuleAsyncCodeFixConstants.UpdateToAsyncEquivalentsDescription), diagnostic);
     }
 
-    private static BaseListSyntax GetBaseTypes(TypeDeclarationSyntax typeNode)
+    private static BaseListSyntax? GetBaseTypes(TypeDeclarationSyntax typeNode)
     {
       var currentBaseList = typeNode.BaseList;
+      if (currentBaseList is null)
+      {
+        return null;
+      }
 
       var list = new SeparatedSyntaxList<BaseTypeSyntax>();
 
-      foreach (var baseTypeNode in typeNode.BaseList.DescendantNodes().OfType<SimpleBaseTypeSyntax>())
+      foreach (var baseTypeNode in typeNode.BaseList!.DescendantNodes().OfType<SimpleBaseTypeSyntax>())
       {
         var baseTypeNodeIdentifier = baseTypeNode.DescendantNodes().OfType<IdentifierNameSyntax>().Single();
 
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/BusinessRuleDoesNotUseAddMethodsOnContextAnalyzer.cs b/Source/Csla.Analyzers/Csla.Analyzers/BusinessRuleDoesNotUseAddMethodsOnContextAnalyzer.cs
index 293d6b6820..f6fe823b94 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/BusinessRuleDoesNotUseAddMethodsOnContextAnalyzer.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/BusinessRuleDoesNotUseAddMethodsOnContextAnalyzer.cs
@@ -47,6 +47,10 @@ private static void AnalyzeMethodDeclaration(SyntaxNodeAnalysisContext context)
       if (!methodNode.ContainsDiagnostics)
       {
         var methodSymbol = context.SemanticModel.GetDeclaredSymbol(methodNode);
+        if (methodSymbol is null)
+        {
+          return;
+        }
         var typeSymbol = methodSymbol.ContainingType;
 
         if (typeSymbol.IsBusinessRule() && 
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/CheckConstructorsAnalyzer.cs b/Source/Csla.Analyzers/Csla.Analyzers/CheckConstructorsAnalyzer.cs
index d4136e1d32..ad8cfa54a1 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/CheckConstructorsAnalyzer.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/CheckConstructorsAnalyzer.cs
@@ -56,9 +56,9 @@ private static void AnalyzeClassDeclaration(SyntaxNodeAnalysisContext context)
       var classNode = (ClassDeclarationSyntax)context.Node;
       var classSymbol = context.SemanticModel.GetDeclaredSymbol(classNode);
 
-      if (classSymbol.IsStereotype() && !(classSymbol?.IsAbstract).Value)
+      if (classSymbol.IsStereotype() && !classSymbol.IsAbstract)
       {
-        foreach (var constructor in classSymbol?.Constructors)
+        foreach (var constructor in classSymbol.Constructors)
         {
           if (!constructor.IsStatic)
           {
@@ -86,7 +86,7 @@ private static void AnalyzeClassDeclaration(SyntaxNodeAnalysisContext context)
 
         if (!hasPublicNoArgumentConstructor)
         {
-          var properties = new Dictionary<string, string>
+          var properties = new Dictionary<string, string?>
           {
             [PublicNoArgumentConstructorIsMissingConstants.HasNonPublicNoArgumentConstructor] = hasNonPublicNoArgumentConstructor.ToString()
           }.ToImmutableDictionary();
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/CheckConstructorsAnalyzerPublicConstructorCodeFix.cs b/Source/Csla.Analyzers/Csla.Analyzers/CheckConstructorsAnalyzerPublicConstructorCodeFix.cs
index 251616f0d5..696ef952f1 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/CheckConstructorsAnalyzerPublicConstructorCodeFix.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/CheckConstructorsAnalyzerPublicConstructorCodeFix.cs
@@ -35,11 +35,18 @@ public sealed class CheckConstructorsAnalyzerPublicConstructorCodeFix
     public override async Task RegisterCodeFixesAsync(CodeFixContext context)
     {
       var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
-
+      if (root is null)
+      {
+        return;
+      }
       context.CancellationToken.ThrowIfCancellationRequested();
 
       var diagnostic = context.Diagnostics.First();
       var classNode = root.FindNode(diagnostic.Location.SourceSpan) as ClassDeclarationSyntax;
+      if (classNode is null)
+      {
+        return;
+      }
 
       context.CancellationToken.ThrowIfCancellationRequested();
 
@@ -51,14 +58,16 @@ public override async Task RegisterCodeFixesAsync(CodeFixContext context)
         if (context.Document.SupportsSemanticModel)
         {
           var model = await context.Document.GetSemanticModelAsync(context.CancellationToken).ConfigureAwait(false);
-          AddCodeFixWithUpdatingNonPublicConstructor(
-            context, root, diagnostic, classNode, model);
+          if (model is null)
+          {
+            return;
+          }
+          AddCodeFixWithUpdatingNonPublicConstructor(context, root, diagnostic, classNode, model);
         }
       }
       else
       {
-        AddCodeFixWithNewPublicConstructor(
-          context, root, diagnostic, classNode);
+        AddCodeFixWithNewPublicConstructor(context, root, diagnostic, classNode);
       }
     }
 
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/Csla.Analyzers.csproj b/Source/Csla.Analyzers/Csla.Analyzers/Csla.Analyzers.csproj
index d4dc04d472..9d86e04b87 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/Csla.Analyzers.csproj
+++ b/Source/Csla.Analyzers/Csla.Analyzers/Csla.Analyzers.csproj
@@ -17,6 +17,10 @@
     <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.11.0" PrivateAssets="all" />
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="4.10.0" PrivateAssets="all" />
     <PackageReference Update="NETStandard.Library" PrivateAssets="all" />
+    <PackageReference Include="Polyfill" Version="7.4.0">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
+    </PackageReference>
   </ItemGroup>
 
   <ItemGroup>
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/DoesChildOperationHaveRunLocalAnalyzer.cs b/Source/Csla.Analyzers/Csla.Analyzers/DoesChildOperationHaveRunLocalAnalyzer.cs
index 10ec100d86..908542e0a1 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/DoesChildOperationHaveRunLocalAnalyzer.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/DoesChildOperationHaveRunLocalAnalyzer.cs
@@ -42,6 +42,11 @@ private static void AnalyzeMethodDeclaration(SyntaxNodeAnalysisContext context)
       var methodNode = (MethodDeclarationSyntax)context.Node;
 
       var methodSymbol = context.SemanticModel.GetDeclaredSymbol(methodNode);
+      if (methodSymbol is null)
+      {
+        return;
+      }
+
       var typeSymbol = methodSymbol.ContainingType;
 
       if (typeSymbol.IsStereotype() && methodSymbol.IsChildDataPortalOperation() &&
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/DoesChildOperationHaveRunLocalRemoveAttributeCodeFix.cs b/Source/Csla.Analyzers/Csla.Analyzers/DoesChildOperationHaveRunLocalRemoveAttributeCodeFix.cs
index e6c50382c0..4ed2ada81a 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/DoesChildOperationHaveRunLocalRemoveAttributeCodeFix.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/DoesChildOperationHaveRunLocalRemoveAttributeCodeFix.cs
@@ -33,18 +33,25 @@ public sealed class DoesChildOperationHaveRunLocalRemoveAttributeCodeFix
     public override async Task RegisterCodeFixesAsync(CodeFixContext context)
     {
       var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
+      if (root is null)
+      {
+        return;
+      }
 
       context.CancellationToken.ThrowIfCancellationRequested();
 
       var diagnostic = context.Diagnostics.First();
       var methodNode = root.FindNode(diagnostic.Location.SourceSpan) as MethodDeclarationSyntax;
+      if (methodNode is null)
+      {
+        return;
+      }
 
       context.CancellationToken.ThrowIfCancellationRequested();
       await AddCodeFixAsync(context, root, diagnostic, methodNode);
     }
 
-    private static async Task AddCodeFixAsync(CodeFixContext context, SyntaxNode root,
-      Diagnostic diagnostic, MethodDeclarationSyntax methodNode)
+    private static async Task AddCodeFixAsync(CodeFixContext context, SyntaxNode root, Diagnostic diagnostic, MethodDeclarationSyntax methodNode)
     {
       var newRoot = root;
 
@@ -55,7 +62,16 @@ private static async Task AddCodeFixAsync(CodeFixContext context, SyntaxNode roo
       {
         foreach (var attribute in methodSymbol.GetAttributes().Where(_ => _.AttributeClass.IsRunLocalAttribute()))
         {
+          if (attribute.ApplicationSyntaxReference is null)
+          {
+            continue;
+          }
+
           newRoot = newRoot.RemoveNode(await attribute.ApplicationSyntaxReference.GetSyntaxAsync(), SyntaxRemoveOptions.KeepNoTrivia);
+          if (newRoot is null)
+          {
+            return;
+          }
         }
       }
 
@@ -72,6 +88,10 @@ private static async Task AddCodeFixAsync(CodeFixContext context, SyntaxNode roo
       foreach(var attributeListToRemove in attributeListsToRemove)
       {
         newRoot = newRoot.RemoveNode(attributeListToRemove, SyntaxRemoveOptions.KeepEndOfLine);
+        if (newRoot is null)
+        {
+          return;
+        }
       }
 
       context.RegisterCodeFix(
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/DoesOperationHaveAttributeAddAttributeCodeFix.cs b/Source/Csla.Analyzers/Csla.Analyzers/DoesOperationHaveAttributeAddAttributeCodeFix.cs
index 5e3476c8eb..4fcde148f7 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/DoesOperationHaveAttributeAddAttributeCodeFix.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/DoesOperationHaveAttributeAddAttributeCodeFix.cs
@@ -50,11 +50,19 @@ public sealed class DoesOperationHaveAttributeAddAttributeCodeFix
     public override async Task RegisterCodeFixesAsync(CodeFixContext context)
     {
       var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
+      if (root is null)
+      {
+        return;
+      }
 
       context.CancellationToken.ThrowIfCancellationRequested();
 
       var diagnostic = context.Diagnostics.First();
       var methodNode = root.FindNode(diagnostic.Location.SourceSpan) as MethodDeclarationSyntax;
+      if (methodNode is null)
+      {
+        return;
+      }
 
       context.CancellationToken.ThrowIfCancellationRequested();
 
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/DoesOperationHaveAttributeAnalyzer.cs b/Source/Csla.Analyzers/Csla.Analyzers/DoesOperationHaveAttributeAnalyzer.cs
index 87792a4e60..09cf9b59fd 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/DoesOperationHaveAttributeAnalyzer.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/DoesOperationHaveAttributeAnalyzer.cs
@@ -42,6 +42,10 @@ private static void AnalyzeMethodDeclaration(SyntaxNodeAnalysisContext context)
       var methodNode = (MethodDeclarationSyntax)context.Node;
 
       var methodSymbol = context.SemanticModel.GetDeclaredSymbol(methodNode);
+      if (methodSymbol is null)
+      {
+        return;
+      }
       var typeSymbol = methodSymbol.ContainingType;
 
       if (typeSymbol.IsStereotype())
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/EvaluateManagedBackingFieldsAnalyzer.cs b/Source/Csla.Analyzers/Csla.Analyzers/EvaluateManagedBackingFieldsAnalyzer.cs
index 7466405569..1faa2e7d0c 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/EvaluateManagedBackingFieldsAnalyzer.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/EvaluateManagedBackingFieldsAnalyzer.cs
@@ -58,10 +58,8 @@ private static void AnalyzeFieldDeclaration(SyntaxNodeAnalysisContext context)
             {
               foreach (var classMember in classSymbol.GetMembers())
               {
-                if (classMember.Kind == SymbolKind.Property)
+                if (classMember.Kind == SymbolKind.Property && classMember is IPropertySymbol classProperty)
                 {
-                  var classProperty = classMember as IPropertySymbol;
-
                   if (!classProperty.IsIndexer)
                   {
                     if (DetermineIfPropertyUsesField(context, fieldSymbol, classProperty))
@@ -93,9 +91,7 @@ private static void CheckForDiagnostics(SyntaxNodeAnalysisContext context, Field
       }
     }
 
-    private static bool DetermineIfPropertyUsesField(SyntaxNodeAnalysisContext context, 
-      IFieldSymbol fieldSymbol, IPropertySymbol classProperty, 
-      Func<PropertyDeclarationSyntax, SyntaxNode> propertyBody)
+    private static bool DetermineIfPropertyUsesField(SyntaxNodeAnalysisContext context, IFieldSymbol fieldSymbol, IPropertySymbol classProperty, Func<PropertyDeclarationSyntax, SyntaxNode?> propertyBody)
     {
       var root = context.Node.SyntaxTree.GetRoot();
       var rootSpan = root.FullSpan;
@@ -117,15 +113,14 @@ private static bool DetermineIfPropertyUsesField(SyntaxNodeAnalysisContext conte
       return false;
     }
 
-    private static bool DetermineIfPropertyUsesField(SyntaxNodeAnalysisContext context,
-      IFieldSymbol fieldSymbol, IPropertySymbol classProperty)
+    private static bool DetermineIfPropertyUsesField(SyntaxNodeAnalysisContext context, IFieldSymbol fieldSymbol, IPropertySymbol classProperty)
     {
       if (classProperty.GetMethod != null)
       {
         return DetermineIfPropertyUsesField(
           context, fieldSymbol, classProperty,
           propertyNode => propertyNode.ExpressionBody as SyntaxNode ??
-            propertyNode.AccessorList.Accessors.Single(
+            propertyNode.AccessorList?.Accessors.Single(
               _ => _.IsKind(SyntaxKind.GetAccessorDeclaration)));
       }
 
@@ -133,7 +128,7 @@ private static bool DetermineIfPropertyUsesField(SyntaxNodeAnalysisContext conte
       {
         return DetermineIfPropertyUsesField(
           context, fieldSymbol, classProperty,
-          propertyNode => propertyNode.AccessorList.Accessors.Single(
+          propertyNode => propertyNode.AccessorList?.Accessors.Single(
             _ => _.IsKind(SyntaxKind.SetAccessorDeclaration)));
       }
 
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/EvaluateManagedBackingFieldsCodeFix.cs b/Source/Csla.Analyzers/Csla.Analyzers/EvaluateManagedBackingFieldsCodeFix.cs
index 005c8c0ac3..2a4b686fce 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/EvaluateManagedBackingFieldsCodeFix.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/EvaluateManagedBackingFieldsCodeFix.cs
@@ -31,6 +31,10 @@ public sealed class EvaluateManagedBackingFieldsCodeFix
     public override async Task RegisterCodeFixesAsync(CodeFixContext context)
     {
       var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
+      if (root is null)
+      {
+        return;
+      }
 
       context.CancellationToken.ThrowIfCancellationRequested();
 
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/EvaluateManagedBackingFieldsWalker.cs b/Source/Csla.Analyzers/Csla.Analyzers/EvaluateManagedBackingFieldsWalker.cs
index 46ebcb4c5f..5143ca8a1e 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/EvaluateManagedBackingFieldsWalker.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/EvaluateManagedBackingFieldsWalker.cs
@@ -8,7 +8,7 @@ namespace Csla.Analyzers
   internal sealed class EvaluateManagedBackingFieldsWalker
     : CSharpSyntaxWalker
   {
-    internal EvaluateManagedBackingFieldsWalker(SyntaxNode node, SemanticModel model, IFieldSymbol fieldSymbol)
+    internal EvaluateManagedBackingFieldsWalker(SyntaxNode? node, SemanticModel model, IFieldSymbol fieldSymbol)
     {
       (FieldSymbol, Model) = (fieldSymbol, model);
       Visit(node);
@@ -17,6 +17,10 @@ internal EvaluateManagedBackingFieldsWalker(SyntaxNode node, SemanticModel model
     public override void VisitInvocationExpression(InvocationExpressionSyntax node)
     {
       var invocationSymbol = Model.GetSymbolInfo(node).Symbol as IMethodSymbol;
+      if (invocationSymbol is null)
+      {
+        return;
+      }
 
       if (invocationSymbol.IsPropertyInfoManagementMethod())
       {
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/EvaluateOperationAttributeUsageAnalyzer.cs b/Source/Csla.Analyzers/Csla.Analyzers/EvaluateOperationAttributeUsageAnalyzer.cs
index 7e60349f30..08ff445fea 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/EvaluateOperationAttributeUsageAnalyzer.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/EvaluateOperationAttributeUsageAnalyzer.cs
@@ -40,18 +40,25 @@ public override void Initialize(AnalysisContext context)
     private static void AnalyzerAttributeDeclaration(SyntaxNodeAnalysisContext context)
     {
       var attributeNode = (AttributeSyntax)context.Node;
-      var attributeSymbol = context.SemanticModel.GetSymbolInfo(attributeNode).Symbol.ContainingSymbol as ITypeSymbol;
+      var attributeSymbol = context.SemanticModel.GetSymbolInfo(attributeNode).Symbol?.ContainingSymbol as ITypeSymbol;
 
       if (attributeSymbol.IsDataPortalOperationAttribute())
       {
         var methodNode = attributeNode.FindParent<MethodDeclarationSyntax>();
+        if (methodNode is null)
+        {
+          return;
+        }
         var methodSymbol = context.SemanticModel.GetDeclaredSymbol(methodNode);
+        if (methodSymbol is null)
+        {
+          return;
+        }
         var typeSymbol = methodSymbol.ContainingType;
 
         if (!typeSymbol.IsStereotype() || methodSymbol.IsStatic)
         {
-          context.ReportDiagnostic(Diagnostic.Create(
-            operationUsageRule, attributeNode.GetLocation()));
+          context.ReportDiagnostic(Diagnostic.Create(operationUsageRule, attributeNode.GetLocation()));
         }
       }
     }
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/EvaluatePropertiesForSimplicityAnalyzer.cs b/Source/Csla.Analyzers/Csla.Analyzers/EvaluatePropertiesForSimplicityAnalyzer.cs
index bbf6721a94..523f6faa38 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/EvaluatePropertiesForSimplicityAnalyzer.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/EvaluatePropertiesForSimplicityAnalyzer.cs
@@ -44,6 +44,10 @@ private static void AnalyzePropertyDeclaration(SyntaxNodeAnalysisContext context
       if(!propertyNode.ContainsDiagnostics)
       {
         var propertySymbol = context.SemanticModel.GetDeclaredSymbol(propertyNode);
+        if (propertySymbol is null)
+        {
+          return;
+        }
         var classSymbol = propertySymbol.ContainingType;
 
         var fields = GetFieldDeclarations(propertyNode,context.SemanticModel);
@@ -124,6 +128,10 @@ private static void AnalyzePropertyGetterWithGet(PropertyDeclarationSyntax prope
 
       if (getterWalkerBody.Invocation != null)
       {
+        if (getterBody is null)
+        {
+          return;
+        }
         var getterStatements = getterBody.Statements;
 
         if (getterStatements.Count != 1)
@@ -134,7 +142,7 @@ private static void AnalyzePropertyGetterWithGet(PropertyDeclarationSyntax prope
         }
         else
         {
-          if (!(getterStatements[0] is ReturnStatementSyntax returnNode))
+          if (getterStatements[0] is not ReturnStatementSyntax returnNode)
           {
             context.ReportDiagnostic(Diagnostic.Create(
               onlyUseCslaPropertyMethodsInGetSetRule,
@@ -155,7 +163,7 @@ private static void AnalyzePropertyGetterWithGet(PropertyDeclarationSyntax prope
       }
       else if (getterWalkerExpression.Invocation != null)
       {
-        if (!(getterExpression.Expression is InvocationExpressionSyntax invocation) || invocation != getterWalkerExpression.Invocation)
+        if (getterExpression is not null && (getterExpression.Expression is not InvocationExpressionSyntax invocation || invocation != getterWalkerExpression.Invocation))
         {
           context.ReportDiagnostic(Diagnostic.Create(
             onlyUseCslaPropertyMethodsInGetSetRule,
@@ -186,6 +194,10 @@ private static void AnalyzePropertySetter(PropertyDeclarationSyntax propertyNode
 
       if (setterWalkerBody.Invocation != null)
       {
+        if (setterBody is null)
+        {
+          return;
+        }
         var setterStatements = setterBody.Statements;
 
         if (setterStatements.Count != 1)
@@ -196,7 +208,7 @@ private static void AnalyzePropertySetter(PropertyDeclarationSyntax propertyNode
         }
         else
         {
-          if (!(setterStatements[0] is ExpressionStatementSyntax expressionNode))
+          if (setterStatements[0] is not ExpressionStatementSyntax expressionNode)
           {
             context.ReportDiagnostic(Diagnostic.Create(
               onlyUseCslaPropertyMethodsInGetSetRule,
@@ -217,7 +229,7 @@ private static void AnalyzePropertySetter(PropertyDeclarationSyntax propertyNode
       }
       else if (setterWalkerExpression.Invocation != null)
       {
-        if (!(setterExpression.Expression is InvocationExpressionSyntax invocation) || invocation != setterWalkerExpression.Invocation)
+        if (setterExpression is not null && (setterExpression.Expression is not InvocationExpressionSyntax invocation || invocation != setterWalkerExpression.Invocation))
         {
           context.ReportDiagnostic(Diagnostic.Create(
             onlyUseCslaPropertyMethodsInGetSetRule,
@@ -234,7 +246,7 @@ private static void AnalyzePropertySetter(PropertyDeclarationSyntax propertyNode
     /// <summary>
     /// 
     /// </summary>
-    public static IEnumerable<FieldDeclarationSyntax> GetFieldDeclarations(PropertyDeclarationSyntax propertyDeclaration,SemanticModel semanticModel)
+    public static IEnumerable<FieldDeclarationSyntax> GetFieldDeclarations(PropertyDeclarationSyntax propertyDeclaration, SemanticModel semanticModel)
     {
       var classDeclaration = propertyDeclaration.FirstAncestorOrSelf<ClassDeclarationSyntax>();
       var propertyType = semanticModel.GetTypeInfo(propertyDeclaration.Type).Type;
@@ -245,15 +257,13 @@ public static IEnumerable<FieldDeclarationSyntax> GetFieldDeclarations(PropertyD
       }
 
       // Find all field declarations in the class
-      var fieldDeclarations = classDeclaration.Members
-          .OfType<FieldDeclarationSyntax>();
+      var fieldDeclarations = classDeclaration.Members.OfType<FieldDeclarationSyntax>();
 
       // Filter for static fields
-      return fieldDeclarations
-          .Where(field => FilterField(field,propertyDeclaration, propertyType,semanticModel));
+      return fieldDeclarations.Where(field => FilterField(field,propertyDeclaration, propertyType, semanticModel));
     }
 
-    private static bool FilterField(FieldDeclarationSyntax fieldDeclaration, PropertyDeclarationSyntax propertyDeclaration, ITypeSymbol propertyType,SemanticModel semanticModel)
+    private static bool FilterField(FieldDeclarationSyntax fieldDeclaration, PropertyDeclarationSyntax propertyDeclaration, ITypeSymbol? propertyType, SemanticModel semanticModel)
     {
       var fieldType = semanticModel.GetTypeInfo(fieldDeclaration.Declaration.Type).Type;
       if (fieldType != null && fieldType.OriginalDefinition.ToString() == "Csla.PropertyInfo<T>")
@@ -262,7 +272,8 @@ private static bool FilterField(FieldDeclarationSyntax fieldDeclaration, Propert
         if (SymbolEqualityComparer.Default.Equals(typeArgument, propertyType))
         {
           var initializer = fieldDeclaration.Declaration.Variables
-            .Select(a => a.Initializer.Value)
+            .Where(a => a.Initializer != null)
+            .Select(a => a.Initializer!.Value)
             .OfType<InvocationExpressionSyntax>().Select(w=>w.ArgumentList.Arguments.FirstOrDefault()?.Expression);
           var lambda = initializer
             .OfType<SimpleLambdaExpressionSyntax>()
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/Extensions/ITypeSymbolExtensions.cs b/Source/Csla.Analyzers/Csla.Analyzers/Extensions/ITypeSymbolExtensions.cs
index 47ba2d1cee..72ca87b44e 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/Extensions/ITypeSymbolExtensions.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/Extensions/ITypeSymbolExtensions.cs
@@ -1,4 +1,5 @@
-using Microsoft.CodeAnalysis;
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.CodeAnalysis;
 
 namespace Csla.Analyzers.Extensions
 {
@@ -7,7 +8,7 @@ internal static class ITypeSymbolExtensions
     private static readonly Type[] SerializableTypesByMobileFormatter =
       [typeof(TimeSpan), typeof(DateTimeOffset), typeof(byte[]), typeof(byte[][]), typeof(char[]), typeof(Guid), typeof(List<int>)];
 
-    internal static bool IsBusinessRule(this ITypeSymbol? @this)
+    internal static bool IsBusinessRule([NotNullWhen(true)] this ITypeSymbol? @this)
     {
       return @this != null &&
         (((@this.Name == CslaMemberConstants.Types.IBusinessRule || @this.Name == CslaMemberConstants.Types.IBusinessRuleAsync) &&
@@ -15,7 +16,7 @@ internal static bool IsBusinessRule(this ITypeSymbol? @this)
           (@this.BaseType.IsBusinessRule() || @this.Interfaces.Any(_ => _.IsBusinessRule())));
     }
 
-    internal static bool IsObjectFactory(this ITypeSymbol? @this)
+    internal static bool IsObjectFactory([NotNullWhen(true)] this ITypeSymbol? @this)
     {
       return @this != null &&
         ((@this.Name == CslaMemberConstants.Types.ObjectFactory &&
@@ -23,7 +24,7 @@ internal static bool IsObjectFactory(this ITypeSymbol? @this)
           @this.BaseType.IsObjectFactory());
     }
 
-    internal static bool IsBusinessBase(this ITypeSymbol? @this)
+    internal static bool IsBusinessBase([NotNullWhen(true)] this ITypeSymbol? @this)
     {
       return @this != null &&
         ((@this.Name == CslaMemberConstants.Types.BusinessBase &&
@@ -31,7 +32,7 @@ internal static bool IsBusinessBase(this ITypeSymbol? @this)
           @this.BaseType.IsBusinessBase());
     }
 
-    internal static bool IsInjectable(this ITypeSymbol? @this)
+    internal static bool IsInjectable([NotNullWhen(true)] this ITypeSymbol? @this)
     {
       return @this != null &&
         ((@this.Name == CslaMemberConstants.Types.InjectAttribute &&
@@ -39,7 +40,7 @@ internal static bool IsInjectable(this ITypeSymbol? @this)
           @this.BaseType.IsInjectable());
     }
 
-    internal static bool IsDataPortalOperationAttribute(this ITypeSymbol? @this)
+    internal static bool IsDataPortalOperationAttribute([NotNullWhen(true)] this ITypeSymbol? @this)
     {
       return @this != null &&
         ((@this.Name == CslaMemberConstants.Types.DataPortalOperationAttribute &&
@@ -47,7 +48,7 @@ internal static bool IsDataPortalOperationAttribute(this ITypeSymbol? @this)
           @this.BaseType.IsDataPortalOperationAttribute());
     }
 
-    internal static bool IsDataPortalRootOperationAttribute(this ITypeSymbol? @this)
+    internal static bool IsDataPortalRootOperationAttribute([NotNullWhen(true)] this ITypeSymbol? @this)
     {
       return @this != null &&
         ((@this.Name == CslaMemberConstants.Types.DataPortalRootOperationAttribute &&
@@ -55,7 +56,7 @@ internal static bool IsDataPortalRootOperationAttribute(this ITypeSymbol? @this)
           @this.BaseType.IsDataPortalRootOperationAttribute());
     }
 
-    internal static bool IsDataPortalChildOperationAttribute(this ITypeSymbol? @this)
+    internal static bool IsDataPortalChildOperationAttribute([NotNullWhen(true)] this ITypeSymbol? @this)
     {
       return @this != null &&
         ((@this.Name == CslaMemberConstants.Types.DataPortalChildOperationAttribute &&
@@ -63,7 +64,7 @@ internal static bool IsDataPortalChildOperationAttribute(this ITypeSymbol? @this
           @this.BaseType.IsDataPortalChildOperationAttribute());
     }
 
-    internal static bool IsRunLocalAttribute(this ITypeSymbol @this)
+    internal static bool IsRunLocalAttribute([NotNullWhen(true)] this ITypeSymbol? @this)
     {
       return @this != null &&
         @this.Name == CslaMemberConstants.Types.RunLocalAttribute &&
@@ -114,7 +115,7 @@ internal static bool IsSpecialTypeSerializable(this ITypeSymbol @this)
         specialType == SpecialType.System_DateTime;
     }
 
-    internal static bool IsIPropertyInfo(this ITypeSymbol? @this)
+    internal static bool IsIPropertyInfo([NotNullWhen(true)] this ITypeSymbol? @this)
     {
       return @this != null &&
         ((@this.Name == CslaMemberConstants.Types.IPropertyInfo &&
@@ -122,7 +123,7 @@ internal static bool IsIPropertyInfo(this ITypeSymbol? @this)
           @this.BaseType.IsIPropertyInfo() || @this.Interfaces.Any(_ => _.IsIPropertyInfo()));
     }
 
-    internal static bool IsEditableStereotype(this ITypeSymbol? @this)
+    internal static bool IsEditableStereotype([NotNullWhen(true)] this ITypeSymbol? @this)
     {
       return @this != null &&
         (((@this.Name == CslaMemberConstants.Types.BusinessBase ||
@@ -133,7 +134,7 @@ internal static bool IsEditableStereotype(this ITypeSymbol? @this)
           @this.BaseType.IsEditableStereotype());
     }
 
-    internal static bool IsStereotype(this ITypeSymbol? @this)
+    internal static bool IsStereotype([NotNullWhen(true)] this ITypeSymbol? @this)
     {
       return @this != null &&
         (((@this.Name == CslaMemberConstants.Types.IBusinessObject ||
@@ -142,7 +143,7 @@ internal static bool IsStereotype(this ITypeSymbol? @this)
           (@this.BaseType.IsStereotype() || @this.Interfaces.Any(_ => _.IsStereotype())));
     }
 
-    internal static bool IsMobileObject(this ITypeSymbol? @this)
+    internal static bool IsMobileObject([NotNullWhen(true)] this ITypeSymbol? @this)
     {
       return @this != null &&
         ((@this.Name == CslaMemberConstants.Types.IMobileObject &&
@@ -150,7 +151,7 @@ internal static bool IsMobileObject(this ITypeSymbol? @this)
           (@this.BaseType.IsMobileObject() || @this.Interfaces.Any(_ => _.IsMobileObject())));
     }
 
-    internal static bool IsObjectAuthorizationRulesAttribute(this ITypeSymbol? @this)
+    internal static bool IsObjectAuthorizationRulesAttribute([NotNullWhen(true)] this ITypeSymbol? @this)
     {
       return @this != null &&
         ((@this.Name == CslaMemberConstants.Types.ObjectAuthorizationRulesAttribute &&
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/FindGetOrReadInvocationsWalker.cs b/Source/Csla.Analyzers/Csla.Analyzers/FindGetOrReadInvocationsWalker.cs
index 6f858be9fe..8ceaace52e 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/FindGetOrReadInvocationsWalker.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/FindGetOrReadInvocationsWalker.cs
@@ -8,7 +8,7 @@ namespace Csla.Analyzers
   internal sealed class FindGetOrReadInvocationsWalker
     : CSharpSyntaxWalker
   {
-    internal FindGetOrReadInvocationsWalker(SyntaxNode node, SemanticModel model)
+    internal FindGetOrReadInvocationsWalker(SyntaxNode? node, SemanticModel model)
     {
       Model = model;
       Visit(node);
@@ -17,15 +17,14 @@ internal FindGetOrReadInvocationsWalker(SyntaxNode node, SemanticModel model)
     public override void VisitInvocationExpression(InvocationExpressionSyntax node)
     {
       var symbol = Model.GetSymbolInfo(node);
-      var methodSymbol = symbol.Symbol as IMethodSymbol;
 
-      if (methodSymbol.IsPropertyInfoManagementMethod())
+      if (symbol.Symbol is IMethodSymbol methodSymbol && methodSymbol.IsPropertyInfoManagementMethod())
       {
         Invocation = node;
       }
     }
 
-    internal InvocationExpressionSyntax Invocation { get; private set; }
+    internal InvocationExpressionSyntax? Invocation { get; private set; }
     private SemanticModel Model { get; }
   }
 }
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/FindOperationsWithIncorrectReturnTypeResolveCorrectTypeCodeFix.cs b/Source/Csla.Analyzers/Csla.Analyzers/FindOperationsWithIncorrectReturnTypeResolveCorrectTypeCodeFix.cs
index b8f10bd0dc..a70c75ef7b 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/FindOperationsWithIncorrectReturnTypeResolveCorrectTypeCodeFix.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/FindOperationsWithIncorrectReturnTypeResolveCorrectTypeCodeFix.cs
@@ -33,31 +33,44 @@ public sealed class FindOperationsWithIncorrectReturnTypeResolveCorrectTypeCodeF
     public override async Task RegisterCodeFixesAsync(CodeFixContext context)
     {
       var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
-
+      if (root is null)
+      {
+        return;
+      }
       context.CancellationToken.ThrowIfCancellationRequested();
 
       var diagnostic = context.Diagnostics.First();
       var methodNode = root.FindNode(diagnostic.Location.SourceSpan) as MethodDeclarationSyntax;
+      if (methodNode is null)
+      {
+        return;
+      }
 
       context.CancellationToken.ThrowIfCancellationRequested();
 
       await AddCodeFixAsync(context, root, diagnostic, methodNode);
     }
 
-    private static async Task AddCodeFixAsync(CodeFixContext context, SyntaxNode root,
-      Diagnostic diagnostic, MethodDeclarationSyntax methodNode)
+    private static async Task AddCodeFixAsync(CodeFixContext context, SyntaxNode root, Diagnostic diagnostic, MethodDeclarationSyntax methodNode)
     {
       var model = await context.Document.GetSemanticModelAsync(context.CancellationToken);
       var methodSymbol = model.GetDeclaredSymbol(methodNode);
+      if (methodSymbol is null)
+      {
+        return;
+      }
 
       if(methodSymbol.IsAsync)
       {
-        var newRoot = root.ReplaceNode(methodNode.ReturnType,
-          SyntaxFactory.IdentifierName(typeof(Task).Name));
+        var newRoot = root.ReplaceNode(methodNode.ReturnType, SyntaxFactory.IdentifierName(typeof(Task).Name));
 
         if (!root.HasUsing(FindOperationsWithIncorrectReturnTypeResolveCorrectTypeCodeFixConstants.SystemThreadingTasksNamespace))
         {
-          newRoot = (newRoot as CompilationUnitSyntax).AddUsings(
+          if (newRoot is not CompilationUnitSyntax compilationUnitSyntax)
+          {
+            return;
+          }
+          newRoot = compilationUnitSyntax.AddUsings(
             SyntaxFactory.UsingDirective(SyntaxFactory.ParseName(
               FindOperationsWithIncorrectReturnTypeResolveCorrectTypeCodeFixConstants.SystemThreadingTasksNamespace)));
         }
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/FindOperationsWithIncorrectReturnTypesAnalyzer.cs b/Source/Csla.Analyzers/Csla.Analyzers/FindOperationsWithIncorrectReturnTypesAnalyzer.cs
index dab758e9d9..46d66aeb70 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/FindOperationsWithIncorrectReturnTypesAnalyzer.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/FindOperationsWithIncorrectReturnTypesAnalyzer.cs
@@ -42,6 +42,10 @@ private static void AnalyzeMethodDeclaration(SyntaxNodeAnalysisContext context)
     {
       var methodNode = (MethodDeclarationSyntax)context.Node;
       var methodSymbol = context.SemanticModel.GetDeclaredSymbol(methodNode);
+      if (methodSymbol is null)
+      {
+        return;
+      }
       var typeSymbol = methodSymbol.ContainingType;
 
       if (typeSymbol.IsStereotype() && methodSymbol.IsDataPortalOperation())
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/FindOperationsWithNonSerializableArgumentsAnalyzer.cs b/Source/Csla.Analyzers/Csla.Analyzers/FindOperationsWithNonSerializableArgumentsAnalyzer.cs
index 4c039c7152..28d45c354d 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/FindOperationsWithNonSerializableArgumentsAnalyzer.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/FindOperationsWithNonSerializableArgumentsAnalyzer.cs
@@ -42,6 +42,10 @@ private static void AnalyzeMethodDeclaration(SyntaxNodeAnalysisContext context)
     {
       var methodNode = (MethodDeclarationSyntax)context.Node;
       var methodSymbol = context.SemanticModel.GetDeclaredSymbol(methodNode);
+      if (methodSymbol is null)
+      {
+        return;
+      }
       var typeSymbol = methodSymbol.ContainingType;
 
       if (typeSymbol.IsStereotype() && methodSymbol.IsRootDataPortalOperation())
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/FindRefAndOutParametersInOperationsAnalyzer.cs b/Source/Csla.Analyzers/Csla.Analyzers/FindRefAndOutParametersInOperationsAnalyzer.cs
index e37f661ac4..0a893720ac 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/FindRefAndOutParametersInOperationsAnalyzer.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/FindRefAndOutParametersInOperationsAnalyzer.cs
@@ -46,14 +46,17 @@ private static void AnalyzeMethodDeclaration(SyntaxNodeAnalysisContext context)
       if (!methodNode.ContainsDiagnostics)
       {
         var methodSymbol = context.SemanticModel.GetDeclaredSymbol(methodNode);
+        if (methodSymbol is null)
+        {
+          return;
+        }
         var typeSymbol = methodSymbol.ContainingType;
 
         if (typeSymbol.IsBusinessBase() && methodSymbol.IsDataPortalOperation())
         {
           foreach(var parameterSymbol in methodSymbol.Parameters)
           {
-            if(parameterSymbol.RefKind == RefKind.Out ||
-              parameterSymbol.RefKind == RefKind.Ref)
+            if(parameterSymbol.RefKind == RefKind.Out || parameterSymbol.RefKind == RefKind.Ref)
             {
               context.ReportDiagnostic(Diagnostic.Create(
                 incorrectParameterRule, parameterSymbol.Locations[0]));
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/FindSaveAssignmentIssueAnalyzer.cs b/Source/Csla.Analyzers/Csla.Analyzers/FindSaveAssignmentIssueAnalyzer.cs
index 448608cf4f..2f89432f34 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/FindSaveAssignmentIssueAnalyzer.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/FindSaveAssignmentIssueAnalyzer.cs
@@ -61,20 +61,18 @@ private static void AnalyzeInvocation(SyntaxNodeAnalysisContext context)
 
           if (invocationSymbol?.Name == Constants.SaveMethodNames.Save)
           {
-            CheckForCondition(context, invocationNode,
-              expressionStatementNode, saveResultIsNotAssignedRule);
+            CheckForCondition(context, invocationNode, expressionStatementNode, saveResultIsNotAssignedRule);
           }
           else if (invocationSymbol?.Name == Constants.SaveMethodNames.SaveAsync)
           {
-            CheckForCondition(context, invocationNode,
-              expressionStatementNode, saveAsyncResultIsNotAssignedRule);
+            CheckForCondition(context, invocationNode, expressionStatementNode, saveAsyncResultIsNotAssignedRule);
           }
         }
       }
     }
 
     private static void CheckForCondition(SyntaxNodeAnalysisContext context, InvocationExpressionSyntax invocationNode,
-      ExpressionStatementSyntax expressionStatementParent, DiagnosticDescriptor descriptor)
+      ExpressionStatementSyntax? expressionStatementParent, DiagnosticDescriptor descriptor)
     {
       // Make sure the invocation's containing type is not the same as the class that contains it
       if ((invocationNode.DescendantNodesAndTokens().Any(_ => _.IsKind(SyntaxKind.DotToken)) &&
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/FindSaveAssignmentIssueAnalyzerAddAssignmentCodeFix.cs b/Source/Csla.Analyzers/Csla.Analyzers/FindSaveAssignmentIssueAnalyzerAddAssignmentCodeFix.cs
index 1c638e3a67..7670c45970 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/FindSaveAssignmentIssueAnalyzerAddAssignmentCodeFix.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/FindSaveAssignmentIssueAnalyzerAddAssignmentCodeFix.cs
@@ -32,14 +32,21 @@ public sealed class FindSaveAssignmentIssueAnalyzerAddAssignmentCodeFix
     public override async Task RegisterCodeFixesAsync(CodeFixContext context)
     {
       var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
+      if (root is null)
+      {
+        return;
+      }
 
       context.CancellationToken.ThrowIfCancellationRequested();
 
       var diagnostic = context.Diagnostics.First();
       var invocationNode = root.FindNode(diagnostic.Location.SourceSpan) as InvocationExpressionSyntax;
 
-      var invocationIdentifier = ((invocationNode.Expression as MemberAccessExpressionSyntax)
-        .Expression as IdentifierNameSyntax).Identifier;
+      if (invocationNode?.Expression is not MemberAccessExpressionSyntax memberAccessExpressionSyntax || memberAccessExpressionSyntax.Expression is not IdentifierNameSyntax identifierNameSyntax)
+      {
+        return;
+      }
+      var invocationIdentifier = identifierNameSyntax.Identifier;
       var leadingTrivia = invocationIdentifier.HasLeadingTrivia ? 
         invocationIdentifier.LeadingTrivia : new SyntaxTriviaList();
 
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/FindSaveAssignmentIssueAnalyzerAddAsyncAssignmentCodeFix.cs b/Source/Csla.Analyzers/Csla.Analyzers/FindSaveAssignmentIssueAnalyzerAddAsyncAssignmentCodeFix.cs
index 29c71f6cf1..27b7e8168b 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/FindSaveAssignmentIssueAnalyzerAddAsyncAssignmentCodeFix.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/FindSaveAssignmentIssueAnalyzerAddAsyncAssignmentCodeFix.cs
@@ -33,40 +33,50 @@ public sealed class FindSaveAssignmentIssueAnalyzerAddAsyncAssignmentCodeFix
     public override async Task RegisterCodeFixesAsync(CodeFixContext context)
     {
       var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
+      if (root is null)
+      {
+        return;
+      }
 
       context.CancellationToken.ThrowIfCancellationRequested();
 
       var diagnostic = context.Diagnostics.First();
-      var invocationNode = root.FindNode(diagnostic.Location.SourceSpan) as InvocationExpressionSyntax;
+      if (root.FindNode(diagnostic.Location.SourceSpan) is not InvocationExpressionSyntax invocationNode)
+      {
+        return;
+      }
 
-      var awaitExpressionNode = invocationNode.FindParent<AwaitExpressionSyntax>();
+      if (invocationNode.Expression is not MemberAccessExpressionSyntax memberAccessExpressionSyntax || memberAccessExpressionSyntax.Expression is not IdentifierNameSyntax identifierNameSyntax)
+      {
+        return;
+      }
 
-      if(awaitExpressionNode != null)
+      var awaitExpressionNode = invocationNode.FindParent<AwaitExpressionSyntax>();
+      if (awaitExpressionNode == null)
       {
-        var awaitKeyword = awaitExpressionNode.AwaitKeyword;
-        var leadingTrivia = awaitKeyword.HasLeadingTrivia ?
-          awaitKeyword.LeadingTrivia : new SyntaxTriviaList();
+        return;
+      }
 
-        var newAwaitExpressionNode = awaitExpressionNode.WithAwaitKeyword(
-          awaitKeyword.WithLeadingTrivia(new SyntaxTriviaList()));
-        var invocationIdentifier = ((invocationNode.Expression as MemberAccessExpressionSyntax)
-          .Expression as IdentifierNameSyntax).Identifier;
-        var newInvocationIdentifier = invocationIdentifier.WithLeadingTrivia(new SyntaxTriviaList());
+      var awaitKeyword = awaitExpressionNode.AwaitKeyword;
+      var leadingTrivia = awaitKeyword.HasLeadingTrivia ? awaitKeyword.LeadingTrivia : new SyntaxTriviaList();
 
-        context.CancellationToken.ThrowIfCancellationRequested();
+      var newAwaitExpressionNode = awaitExpressionNode.WithAwaitKeyword(awaitKeyword.WithLeadingTrivia(new SyntaxTriviaList()));
+      var invocationIdentifier = identifierNameSyntax.Identifier;
+      var newInvocationIdentifier = invocationIdentifier.WithLeadingTrivia(new SyntaxTriviaList());
 
-        var simpleAssignmentExpressionNode = SyntaxFactory.AssignmentExpression(SyntaxKind.SimpleAssignmentExpression,
-          SyntaxFactory.IdentifierName(newInvocationIdentifier), newAwaitExpressionNode)
-          .WithLeadingTrivia(leadingTrivia);
+      context.CancellationToken.ThrowIfCancellationRequested();
 
-        var newRoot = root.ReplaceNode(awaitExpressionNode, simpleAssignmentExpressionNode);
+      var simpleAssignmentExpressionNode = SyntaxFactory.AssignmentExpression(SyntaxKind.SimpleAssignmentExpression,
+        SyntaxFactory.IdentifierName(newInvocationIdentifier), newAwaitExpressionNode)
+        .WithLeadingTrivia(leadingTrivia);
 
-        context.RegisterCodeFix(
-          CodeAction.Create(
-            FindSaveAssignmentIssueAnalyzerAddAssignmentCodeFixConstants.AddAssignmentDescription,
-            _ => Task.FromResult(context.Document.WithSyntaxRoot(newRoot)),
-            FindSaveAssignmentIssueAnalyzerAddAssignmentCodeFixConstants.AddAssignmentDescription), diagnostic);
-      }
+      var newRoot = root.ReplaceNode(awaitExpressionNode, simpleAssignmentExpressionNode);
+
+      context.RegisterCodeFix(
+        CodeAction.Create(
+          FindSaveAssignmentIssueAnalyzerAddAssignmentCodeFixConstants.AddAssignmentDescription,
+          _ => Task.FromResult(context.Document.WithSyntaxRoot(newRoot)),
+          FindSaveAssignmentIssueAnalyzerAddAssignmentCodeFixConstants.AddAssignmentDescription), diagnostic);
     }
   }
 }
\ No newline at end of file
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/FindSetOrLoadInvocationsWalker.cs b/Source/Csla.Analyzers/Csla.Analyzers/FindSetOrLoadInvocationsWalker.cs
index 0a29587fa8..81af14e1f6 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/FindSetOrLoadInvocationsWalker.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/FindSetOrLoadInvocationsWalker.cs
@@ -8,7 +8,7 @@ namespace Csla.Analyzers
   internal sealed class FindSetOrLoadInvocationsWalker
     : CSharpSyntaxWalker
   {
-    internal FindSetOrLoadInvocationsWalker(SyntaxNode node, SemanticModel model)
+    internal FindSetOrLoadInvocationsWalker(SyntaxNode? node, SemanticModel model)
     {
       Model = model;
       Visit(node);
@@ -17,15 +17,14 @@ internal FindSetOrLoadInvocationsWalker(SyntaxNode node, SemanticModel model)
     public override void VisitInvocationExpression(InvocationExpressionSyntax node)
     {
       var symbol = Model.GetSymbolInfo(node);
-      var methodSymbol = symbol.Symbol as IMethodSymbol;
 
-      if (methodSymbol.IsPropertyInfoManagementMethod())
+      if (symbol.Symbol is IMethodSymbol methodSymbol && methodSymbol.IsPropertyInfoManagementMethod())
       {
         Invocation = node;
       }
     }
 
-    internal InvocationExpressionSyntax Invocation { get; private set; }
+    internal InvocationExpressionSyntax? Invocation { get; private set; }
     private SemanticModel Model { get; }
   }
 }
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/IsCompleteCalledInAsynchronousBusinessRuleAnalyzer.cs b/Source/Csla.Analyzers/Csla.Analyzers/IsCompleteCalledInAsynchronousBusinessRuleAnalyzer.cs
index 8569f03b93..0b4dae2ece 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/IsCompleteCalledInAsynchronousBusinessRuleAnalyzer.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/IsCompleteCalledInAsynchronousBusinessRuleAnalyzer.cs
@@ -46,6 +46,10 @@ private static void AnalyzeMethodDeclaration(SyntaxNodeAnalysisContext context)
       if (!methodNode.ContainsDiagnostics)
       {
         var methodSymbol = context.SemanticModel.GetDeclaredSymbol(methodNode);
+        if (methodSymbol is null)
+        {
+          return;
+        }
         var typeSymbol = methodSymbol.ContainingType;
 
         if (typeSymbol.IsBusinessRule() && methodSymbol.Name == "ExecuteAsync" &&
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/IsCompleteCalledInAsynchronousBusinessRuleRemoveCallCodeFix.cs b/Source/Csla.Analyzers/Csla.Analyzers/IsCompleteCalledInAsynchronousBusinessRuleRemoveCallCodeFix.cs
index f88370d3fb..a87b3f3bf5 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/IsCompleteCalledInAsynchronousBusinessRuleRemoveCallCodeFix.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/IsCompleteCalledInAsynchronousBusinessRuleRemoveCallCodeFix.cs
@@ -35,21 +35,32 @@ public sealed class IsCompleteCalledInAsynchronousBusinessRuleRemoveCallCodeFix
     public override async Task RegisterCodeFixesAsync(CodeFixContext context)
     {
       var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
+      if (root is null)
+      {
+        return;
+      }
 
       context.CancellationToken.ThrowIfCancellationRequested();
 
       var diagnostic = context.Diagnostics.First();
       var methodNode = root.FindNode(diagnostic.Location.SourceSpan) as MethodDeclarationSyntax;
+      if (methodNode is null)
+      {
+        return;
+      }
 
       context.CancellationToken.ThrowIfCancellationRequested();
       await AddCodeFixAsync(context, root, diagnostic, methodNode);
     }
 
-    private static async Task AddCodeFixAsync(CodeFixContext context, SyntaxNode root,
-      Diagnostic diagnostic, MethodDeclarationSyntax methodNode)
+    private static async Task AddCodeFixAsync(CodeFixContext context, SyntaxNode root, Diagnostic diagnostic, MethodDeclarationSyntax methodNode)
     {
       var model = await context.Document.GetSemanticModelAsync(context.CancellationToken);
       var methodSymbol = model.GetDeclaredSymbol(methodNode);
+      if (methodSymbol is null)
+      {
+        return;
+      }
       var contextParameter = methodSymbol.Parameters[0];
 
       var newRoot = root;
@@ -60,10 +71,18 @@ private static async Task AddCodeFixAsync(CodeFixContext context, SyntaxNode roo
           return model.GetSymbolInfo(invocation.Expression).Symbol is IMethodSymbol invocationSymbol &&
             invocationSymbol.Name == "Complete" && SymbolEqualityComparer.Default.Equals(invocationSymbol.ContainingType, contextParameter.Type);
         })
-        .Select(invocation => invocation.FindParent<ExpressionStatementSyntax>());
+        .Select(invocation => invocation.FindParent<ExpressionStatementSyntax>())
+        .Where(i => i is not null)
+        .Select(s => s!)
+        ;
 
-      newRoot = newRoot.RemoveNodes(completeInvocations, SyntaxRemoveOptions.KeepExteriorTrivia | SyntaxRemoveOptions.KeepDirectives)
-        .WithAdditionalAnnotations(Formatter.Annotation);
+      newRoot = newRoot.RemoveNodes(completeInvocations, SyntaxRemoveOptions.KeepExteriorTrivia | SyntaxRemoveOptions.KeepDirectives);
+      if (newRoot is null)
+      {
+        return;
+      }
+      
+      newRoot = newRoot.WithAdditionalAnnotations(Formatter.Annotation);
 
       context.RegisterCodeFix(
         CodeAction.Create(
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/IsOperationMethodPublicAnalyzer.cs b/Source/Csla.Analyzers/Csla.Analyzers/IsOperationMethodPublicAnalyzer.cs
index 79f9ed13fa..0dc0edb0de 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/IsOperationMethodPublicAnalyzer.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/IsOperationMethodPublicAnalyzer.cs
@@ -51,6 +51,10 @@ private static void AnalyzeMethodDeclaration(SyntaxNodeAnalysisContext context)
     {
       var methodNode = (MethodDeclarationSyntax)context.Node;
       var methodSymbol = context.SemanticModel.GetDeclaredSymbol(methodNode);
+      if (methodSymbol is null)
+      {
+        return;
+      }
       var typeSymbol = methodSymbol.ContainingType;
 
       if (typeSymbol.IsStereotype() && methodSymbol.IsDataPortalOperation() &&
@@ -63,7 +67,7 @@ private static void AnalyzeMethodDeclaration(SyntaxNodeAnalysisContext context)
         }
         else
         {
-          var properties = new Dictionary<string, string>
+          var properties = new Dictionary<string, string?>
           {
             [IsOperationMethodPublicAnalyzerConstants.IsSealed] = typeSymbol.IsSealed.ToString()
           }.ToImmutableDictionary();
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/IsOperationMethodPublicMakeNonPublicCodeFix.cs b/Source/Csla.Analyzers/Csla.Analyzers/IsOperationMethodPublicMakeNonPublicCodeFix.cs
index c349f5efaf..7f79577305 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/IsOperationMethodPublicMakeNonPublicCodeFix.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/IsOperationMethodPublicMakeNonPublicCodeFix.cs
@@ -32,11 +32,19 @@ public sealed class IsOperationMethodPublicMakeNonPublicCodeFix
     public override async Task RegisterCodeFixesAsync(CodeFixContext context)
     {
       var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
+      if (root is null)
+      {
+        return;
+      }
 
       context.CancellationToken.ThrowIfCancellationRequested();
 
       var diagnostic = context.Diagnostics.First();
       var methodNode = root.FindNode(diagnostic.Location.SourceSpan) as MethodDeclarationSyntax;
+      if (methodNode is null)
+      {
+        return;
+      }
 
       context.CancellationToken.ThrowIfCancellationRequested();
 
diff --git a/Source/Csla.Analyzers/Csla.Analyzers/ObjectAuthorizationRulesAttributeAnalyzer.cs b/Source/Csla.Analyzers/Csla.Analyzers/ObjectAuthorizationRulesAttributeAnalyzer.cs
index a0fd61dc7e..0e1955f98b 100644
--- a/Source/Csla.Analyzers/Csla.Analyzers/ObjectAuthorizationRulesAttributeAnalyzer.cs
+++ b/Source/Csla.Analyzers/Csla.Analyzers/ObjectAuthorizationRulesAttributeAnalyzer.cs
@@ -56,6 +56,10 @@ private static void AnalyzeMethodDeclaration(SyntaxNodeAnalysisContext context)
       var methodNode = (MethodDeclarationSyntax)context.Node;
 
       var methodSymbol = context.SemanticModel.GetDeclaredSymbol(methodNode);
+      if (methodSymbol is null)
+      {
+        return;
+      }
       var typeSymbol = methodSymbol.ContainingType;
 
       if (typeSymbol.IsStereotype())