diff --git a/packages/core/lib/managed_auth.dart b/packages/core/lib/managed_auth.dart
index 6ca9a647e..8d5e6b3a4 100644
--- a/packages/core/lib/managed_auth.dart
+++ b/packages/core/lib/managed_auth.dart
@@ -48,7 +48,7 @@ class ManagedAuthToken extends ManagedObject<_ManagedAuthToken>
   /// Instance from an [AuthToken].
   ManagedAuthToken.fromToken(AuthToken t) : super() {
     final tokenResourceOwner =
-        entity.relationships!["resourceOwner"]!.destinationEntity.instanceOf();
+        entity.relationships["resourceOwner"]!.destinationEntity.instanceOf();
     tokenResourceOwner["id"] = t.resourceOwnerIdentifier;
     this
       ..accessToken = t.accessToken
@@ -64,7 +64,7 @@ class ManagedAuthToken extends ManagedObject<_ManagedAuthToken>
   /// Instance from an [AuthCode].
   ManagedAuthToken.fromCode(AuthCode code) : super() {
     final tokenResourceOwner =
-        entity.relationships!["resourceOwner"]!.destinationEntity.instanceOf();
+        entity.relationships["resourceOwner"]!.destinationEntity.instanceOf();
     tokenResourceOwner["id"] = code.resourceOwnerIdentifier;
 
     this
diff --git a/packages/core/lib/src/db/managed/entity.dart b/packages/core/lib/src/db/managed/entity.dart
index cd502cf7f..e3f0f402f 100644
--- a/packages/core/lib/src/db/managed/entity.dart
+++ b/packages/core/lib/src/db/managed/entity.dart
@@ -58,7 +58,7 @@ class ManagedEntity implements APIComponentDocumenter {
   /// transient property declared in the instance type.
   /// The keys are the case-sensitive name of the attribute. Values that represent a relationship to another object
   /// are not stored in [attributes].
-  late Map<String?, ManagedAttributeDescription?> attributes;
+  late Map<String, ManagedAttributeDescription?> attributes;
 
   /// All relationship values of this entity.
   ///
@@ -68,7 +68,7 @@ class ManagedEntity implements APIComponentDocumenter {
   /// for [ManagedRelationshipType.hasMany] or [ManagedRelationshipType.hasOne] properties, as those values are derived by the foreign key reference
   /// on the inverse relationship property.
   /// Keys are the case-sensitive name of the relationship.
-  Map<String, ManagedRelationshipDescription?>? relationships;
+  late Map<String, ManagedRelationshipDescription?> relationships;
 
   /// All properties (relationships and attributes) of this entity.
   ///
@@ -76,9 +76,7 @@ class ManagedEntity implements APIComponentDocumenter {
   /// or [ManagedRelationshipDescription]. This is the concatenation of [attributes] and [relationships].
   Map<String, ManagedPropertyDescription?> get properties {
     final all = Map<String, ManagedPropertyDescription?>.from(attributes);
-    if (relationships != null) {
-      all.addAll(relationships!);
-    }
+    all.addAll(relationships);
     return all;
   }
 
@@ -117,7 +115,7 @@ class ManagedEntity implements APIComponentDocumenter {
       );
 
       elements.addAll(
-        relationships!.values
+        relationships.values
             .where(
               (prop) =>
                   prop!.isIncludedInDefaultResultSet &&
@@ -213,7 +211,7 @@ class ManagedEntity implements APIComponentDocumenter {
     final propertyName = elements.first!.name;
     final attribute = attributes[propertyName];
     if (attribute == null) {
-      if (relationships!.containsKey(propertyName)) {
+      if (relationships.containsKey(propertyName)) {
         throw ArgumentError(
             "Invalid property selection. Property '$propertyName' on "
             "'$name' "
@@ -258,7 +256,7 @@ class ManagedEntity implements APIComponentDocumenter {
     }
 
     final propertyName = elements.first!.name;
-    final desc = relationships![propertyName];
+    final desc = relationships[propertyName];
     if (desc == null) {
       throw ArgumentError(
         "Invalid property selection. Relationship named '$propertyName' on table '$tableName' is not a relationship.",
@@ -344,7 +342,7 @@ class ManagedEntity implements APIComponentDocumenter {
     });
 
     buf.writeln("Relationships:");
-    relationships!.forEach((name, rel) {
+    relationships.forEach((name, rel) {
       buf.writeln("\t$rel");
     });
 
diff --git a/packages/core/lib/src/db/managed/property_description.dart b/packages/core/lib/src/db/managed/property_description.dart
index 4c23d5baf..325470348 100644
--- a/packages/core/lib/src/db/managed/property_description.dart
+++ b/packages/core/lib/src/db/managed/property_description.dart
@@ -460,11 +460,11 @@ class ManagedRelationshipDescription extends ManagedPropertyDescription {
   final ManagedRelationshipType relationshipType;
 
   /// The name of the [ManagedRelationshipDescription] on [destinationEntity] that represents the inverse of this relationship.
-  final String? inverseKey;
+  final String inverseKey;
 
   /// The [ManagedRelationshipDescription] on [destinationEntity] that represents the inverse of this relationship.
   ManagedRelationshipDescription? get inverse =>
-      destinationEntity.relationships![inverseKey];
+      destinationEntity.relationships[inverseKey];
 
   /// Whether or not this relationship is on the belonging side.
   bool get isBelongsTo => relationshipType == ManagedRelationshipType.belongsTo;
diff --git a/packages/core/lib/src/db/managed/set.dart b/packages/core/lib/src/db/managed/set.dart
index d1d55e3a1..21cdea9ab 100644
--- a/packages/core/lib/src/db/managed/set.dart
+++ b/packages/core/lib/src/db/managed/set.dart
@@ -36,7 +36,7 @@ class ManagedSet<InstanceType extends ManagedObject> extends Object
     _innerValues = List<InstanceType>.from(items);
   }
 
-  late List<InstanceType> _innerValues;
+  late final List<InstanceType> _innerValues;
 
   /// The number of elements in this set.
   @override
diff --git a/packages/core/lib/src/db/query/mixin.dart b/packages/core/lib/src/db/query/mixin.dart
index 1acbb1139..49670723f 100644
--- a/packages/core/lib/src/db/query/mixin.dart
+++ b/packages/core/lib/src/db/query/mixin.dart
@@ -29,8 +29,8 @@ mixin QueryMixin<InstanceType extends ManagedObject>
   QuerySortPredicate? sortPredicate;
 
   QueryPage? pageDescriptor;
-  List<QuerySortDescriptor>? sortDescriptors;
-  Map<ManagedRelationshipDescription, Query>? subQueries;
+  final List<QuerySortDescriptor> sortDescriptors = <QuerySortDescriptor>[];
+  final Map<ManagedRelationshipDescription, Query> subQueries = {};
 
   QueryMixin? _parentQuery;
   List<QueryExpression<dynamic, dynamic>> expressions = [];
@@ -113,8 +113,7 @@ mixin QueryMixin<InstanceType extends ManagedObject>
   ) {
     final attribute = entity.identifyAttribute(propertyIdentifier);
 
-    sortDescriptors ??= <QuerySortDescriptor>[];
-    sortDescriptors!.add(QuerySortDescriptor(attribute.name, order));
+    sortDescriptors.add(QuerySortDescriptor(attribute.name, order));
   }
 
   @override
@@ -156,7 +155,7 @@ mixin QueryMixin<InstanceType extends ManagedObject>
   Query<T> _createSubquery<T extends ManagedObject>(
     ManagedRelationshipDescription fromRelationship,
   ) {
-    if (subQueries?.containsKey(fromRelationship) ?? false) {
+    if (subQueries.containsKey(fromRelationship)) {
       throw StateError(
         "Invalid query. Cannot join same property more than once.",
       );
@@ -165,8 +164,8 @@ mixin QueryMixin<InstanceType extends ManagedObject>
     // Ensure we don't cyclically join
     var parent = _parentQuery;
     while (parent != null) {
-      if (parent.subQueries!.containsKey(fromRelationship.inverse)) {
-        final validJoins = fromRelationship.entity.relationships!.values
+      if (parent.subQueries.containsKey(fromRelationship.inverse)) {
+        final validJoins = fromRelationship.entity.relationships.values
             .where((r) => !identical(r, fromRelationship))
             .map((r) => "'${r!.name}'")
             .join(", ");
@@ -183,11 +182,9 @@ mixin QueryMixin<InstanceType extends ManagedObject>
       parent = parent._parentQuery;
     }
 
-    subQueries ??= {};
-
     final subquery = Query<T>(context);
     (subquery as QueryMixin)._parentQuery = this;
-    subQueries![fromRelationship] = subquery;
+    subQueries[fromRelationship] = subquery;
 
     return subquery;
   }
diff --git a/packages/core/lib/src/db/query/predicate.dart b/packages/core/lib/src/db/query/predicate.dart
index 3bd6b1af3..3929c116e 100644
--- a/packages/core/lib/src/db/query/predicate.dart
+++ b/packages/core/lib/src/db/query/predicate.dart
@@ -36,20 +36,15 @@ class QueryPredicate {
   ///
   /// If [predicates] is null or empty, an empty predicate is returned. If [predicates] contains only
   /// one predicate, that predicate is returned.
-  factory QueryPredicate.and(Iterable<QueryPredicate?>? predicates) {
-    final predicateList = predicates
-        ?.where((p) => p?.format != null && p!.format.isNotEmpty)
-        .toList();
-    if (predicateList == null) {
-      return QueryPredicate.empty();
-    }
+  factory QueryPredicate.and(Iterable<QueryPredicate> predicates) {
+    final predicateList = predicates.where((p) => p.format.isNotEmpty).toList();
 
     if (predicateList.isEmpty) {
       return QueryPredicate.empty();
     }
 
     if (predicateList.length == 1) {
-      return predicateList.first!;
+      return predicateList.first;
     }
 
     // If we have duplicate keys anywhere, we need to disambiguate them.
@@ -57,7 +52,7 @@ class QueryPredicate {
     final allFormatStrings = [];
     final valueMap = <String, dynamic>{};
     for (final predicate in predicateList) {
-      final duplicateKeys = predicate!.parameters.keys
+      final duplicateKeys = predicate.parameters.keys
           .where((k) => valueMap.keys.contains(k))
           .toList();
 
diff --git a/packages/core/lib/src/db/query/query.dart b/packages/core/lib/src/db/query/query.dart
index 3cffcf6d1..acb7dbfc6 100644
--- a/packages/core/lib/src/db/query/query.dart
+++ b/packages/core/lib/src/db/query/query.dart
@@ -412,7 +412,7 @@ abstract class Query<InstanceType extends ManagedObject> {
   ///       var q = Query<User>()
   ///           ..where.id = whereEqualTo(1);
   ///       var deletedCount = await q.delete();
-  Future<int?> delete();
+  Future<int> delete();
 }
 
 /// Order value for [Query.pageBy] and [Query.sortBy].
diff --git a/packages/core/lib/src/runtime/orm_impl.dart b/packages/core/lib/src/runtime/orm_impl.dart
index 73b2ef9a2..76a3af7f7 100644
--- a/packages/core/lib/src/runtime/orm_impl.dart
+++ b/packages/core/lib/src/runtime/orm_impl.dart
@@ -438,8 +438,8 @@ return entity.symbolMap[Symbol(symbolName)];
     final className = MirrorSystem.getName(instanceType.simpleName);
     final originalFileUri = instanceType.location!.sourceUri.toString();
     final relationshipsStr = (await Future.wait(
-      entity.relationships!.keys.map((name) async {
-        return "'$name': ${await _getRelationshipInstantiator(ctx, entity.relationships![name]!, importUris: importUris)}";
+      entity.relationships.keys.map((name) async {
+        return "'$name': ${await _getRelationshipInstantiator(ctx, entity.relationships[name]!, importUris: importUris)}";
       }),
     ))
         .join(", ");
@@ -453,7 +453,7 @@ return entity.symbolMap[Symbol(symbolName)];
 
     // Need to import any relationships types and metadata types
     // todo: limit import of importUris to only show symbols required to replicate metadata
-    final directives = entity.relationships!.values.map((r) {
+    final directives = entity.relationships.values.map((r) {
       var mirror = reflectType(r!.declaredType!);
       if (mirror.isSubtypeOf(reflectType(ManagedSet))) {
         mirror = mirror.typeArguments.first;
@@ -487,7 +487,7 @@ class ManagedEntityRuntimeImpl extends ManagedEntityRuntime {
     _entity.relationships = {$relationshipsStr};
     _entity.validators = [];
     _entity.validators.addAll(_entity.attributes.values.expand((a) => a!.validators));
-    _entity.validators.addAll(_entity.relationships?.values.expand((a) => a!.validators) ?? []);
+    _entity.validators.addAll(_entity.relationships.values.expand((a) => a!.validators));
 
     entity.uniquePropertySet = $uniqueStr;
   }
diff --git a/packages/core/test/db/data_model_test.dart b/packages/core/test/db/data_model_test.dart
index 83c7f9b77..3611539e6 100644
--- a/packages/core/test/db/data_model_test.dart
+++ b/packages/core/test/db/data_model_test.dart
@@ -59,25 +59,25 @@ void main() {
           expect(entity.properties[key] == attr, true);
         });
 
-        entity.relationships!.forEach((key, attr) {
+        entity.relationships.forEach((key, attr) {
           expect(entity.properties[key] == attr, true);
         });
       }
     });
 
     test("Relationships aren't attributes and vice versa", () {
-      expect(dataModel.entityForType(User).relationships!["id"], isNull);
+      expect(dataModel.entityForType(User).relationships["id"], isNull);
       expect(dataModel.entityForType(User).attributes["id"], isNotNull);
 
       expect(dataModel.entityForType(User).attributes["manager"], isNull);
       expect(
-        dataModel.entityForType(User).relationships!["manager"],
+        dataModel.entityForType(User).relationships["manager"],
         isNotNull,
       );
 
       expect(dataModel.entityForType(Manager).attributes["worker"], isNull);
       expect(
-        dataModel.entityForType(Manager).relationships!["worker"],
+        dataModel.entityForType(Manager).relationships["worker"],
         isNotNull,
       );
     });
@@ -138,12 +138,12 @@ void main() {
 
     test("Relationships have appropriate values set", () {
       var entity = dataModel.entityForType(Item);
-      var relDesc = entity.relationships!["user"]!;
+      var relDesc = entity.relationships["user"]!;
       expect(relDesc.isNullable, false);
       expect(relDesc.inverseKey, "items");
       expect(
         relDesc.inverse ==
-            dataModel.entityForType(User).relationships![relDesc.inverseKey],
+            dataModel.entityForType(User).relationships[relDesc.inverseKey],
         true,
       );
       expect(relDesc.deleteRule, DeleteRule.cascade);
@@ -151,12 +151,12 @@ void main() {
       expect(relDesc.relationshipType, ManagedRelationshipType.belongsTo);
 
       entity = dataModel.entityForType(Manager);
-      relDesc = entity.relationships!["worker"]!;
+      relDesc = entity.relationships["worker"]!;
       expect(relDesc.isNullable, true);
       expect(relDesc.inverseKey, "manager");
       expect(
         relDesc.inverse ==
-            dataModel.entityForType(User).relationships![relDesc.inverseKey],
+            dataModel.entityForType(User).relationships[relDesc.inverseKey],
         true,
       );
       expect(relDesc.deleteRule, DeleteRule.nullify);
@@ -164,11 +164,11 @@ void main() {
       expect(relDesc.relationshipType, ManagedRelationshipType.belongsTo);
 
       entity = dataModel.entityForType(User);
-      relDesc = entity.relationships!["manager"]!;
+      relDesc = entity.relationships["manager"]!;
       expect(relDesc.inverseKey, "worker");
       expect(
         relDesc.inverse ==
-            dataModel.entityForType(Manager).relationships![relDesc.inverseKey],
+            dataModel.entityForType(Manager).relationships[relDesc.inverseKey],
         true,
       );
       expect(
@@ -178,7 +178,7 @@ void main() {
       expect(relDesc.relationshipType, ManagedRelationshipType.hasOne);
 
       expect(
-        entity.relationships!["items"]!.relationshipType,
+        entity.relationships["items"]!.relationshipType,
         ManagedRelationshipType.hasMany,
       );
     });
@@ -219,66 +219,66 @@ void main() {
       expect(
         dm
             .entityForType(CyclicLeft)
-            .relationships!["leftRef"]!
+            .relationships["leftRef"]!
             .destinationEntity
             .name,
         "CyclicRight",
       );
       expect(
-        dm.entityForType(CyclicLeft).relationships!["leftRef"]!.inverse!.name,
+        dm.entityForType(CyclicLeft).relationships["leftRef"]!.inverse!.name,
         "from",
       );
       expect(
-        dm.entityForType(CyclicLeft).relationships!["leftRef"]!.isBelongsTo,
+        dm.entityForType(CyclicLeft).relationships["leftRef"]!.isBelongsTo,
         true,
       );
       expect(
         dm
             .entityForType(CyclicLeft)
-            .relationships!["from"]!
+            .relationships["from"]!
             .destinationEntity
             .name,
         "CyclicRight",
       );
       expect(
-        dm.entityForType(CyclicLeft).relationships!["from"]!.inverse!.name,
+        dm.entityForType(CyclicLeft).relationships["from"]!.inverse!.name,
         "rightRef",
       );
       expect(
-        dm.entityForType(CyclicLeft).relationships!["from"]!.isBelongsTo,
+        dm.entityForType(CyclicLeft).relationships["from"]!.isBelongsTo,
         false,
       );
 
       expect(
         dm
             .entityForType(CyclicRight)
-            .relationships!["rightRef"]!
+            .relationships["rightRef"]!
             .destinationEntity
             .name,
         "CyclicLeft",
       );
       expect(
-        dm.entityForType(CyclicRight).relationships!["rightRef"]!.inverse!.name,
+        dm.entityForType(CyclicRight).relationships["rightRef"]!.inverse!.name,
         "from",
       );
       expect(
-        dm.entityForType(CyclicRight).relationships!["rightRef"]!.isBelongsTo,
+        dm.entityForType(CyclicRight).relationships["rightRef"]!.isBelongsTo,
         true,
       );
       expect(
         dm
             .entityForType(CyclicRight)
-            .relationships!["from"]!
+            .relationships["from"]!
             .destinationEntity
             .name,
         "CyclicLeft",
       );
       expect(
-        dm.entityForType(CyclicRight).relationships!["from"]!.inverse!.name,
+        dm.entityForType(CyclicRight).relationships["from"]!.inverse!.name,
         "leftRef",
       );
       expect(
-        dm.entityForType(CyclicRight).relationships!["from"]!.isBelongsTo,
+        dm.entityForType(CyclicRight).relationships["from"]!.isBelongsTo,
         false,
       );
     });
@@ -288,7 +288,7 @@ void main() {
       expect(
         dm
             .entityForType(SelfReferential)
-            .relationships!["parent"]!
+            .relationships["parent"]!
             .destinationEntity
             .name,
         "SelfReferential",
@@ -296,33 +296,29 @@ void main() {
       expect(
         dm
             .entityForType(SelfReferential)
-            .relationships!["parent"]!
+            .relationships["parent"]!
             .inverse!
             .name,
         "child",
       );
       expect(
-        dm.entityForType(SelfReferential).relationships!["parent"]!.isBelongsTo,
+        dm.entityForType(SelfReferential).relationships["parent"]!.isBelongsTo,
         true,
       );
       expect(
         dm
             .entityForType(SelfReferential)
-            .relationships!["child"]!
+            .relationships["child"]!
             .destinationEntity
             .name,
         "SelfReferential",
       );
       expect(
-        dm
-            .entityForType(SelfReferential)
-            .relationships!["child"]!
-            .inverse!
-            .name,
+        dm.entityForType(SelfReferential).relationships["child"]!.inverse!.name,
         "parent",
       );
       expect(
-        dm.entityForType(SelfReferential).relationships!["child"]!.isBelongsTo,
+        dm.entityForType(SelfReferential).relationships["child"]!.isBelongsTo,
         false,
       );
     });
@@ -338,7 +334,7 @@ void main() {
 
       final isManyOf = model
           .entityForType(DoubleRelationshipForeignKeyModel)
-          .relationships!["isManyOf"]!;
+          .relationships["isManyOf"]!;
       expect(isManyOf.inverse!.name, "hasManyOf");
       expect(
         isManyOf.destinationEntity.tableName,
@@ -347,7 +343,7 @@ void main() {
 
       final isOneOf = model
           .entityForType(DoubleRelationshipForeignKeyModel)
-          .relationships!["isOneOf"]!;
+          .relationships["isOneOf"]!;
       expect(isOneOf.inverse!.name, "hasOneOf");
       expect(
         isOneOf.destinationEntity.tableName,
@@ -366,7 +362,7 @@ void main() {
 
       final partial = model
           .entityForType(DoubleRelationshipForeignKeyModel)
-          .relationships!["partial"]!;
+          .relationships["partial"]!;
       expect(
         partial.destinationEntity.tableName,
         model.entityForType(SomeOtherRelationshipModel).tableName,
@@ -391,17 +387,17 @@ void main() {
       expect(totalEntity.attributes["field"]!.isIndexed, true);
       expect(
         totalEntity
-            .relationships!["hasManyRelationship"]!.destinationEntity.tableName,
+            .relationships["hasManyRelationship"]!.destinationEntity.tableName,
         referenceEntity.tableName,
       );
       expect(
-        totalEntity.relationships!["hasManyRelationship"]!.relationshipType,
+        totalEntity.relationships["hasManyRelationship"]!.relationshipType,
         ManagedRelationshipType.hasMany,
       );
 
       expect(
         referenceEntity
-            .relationships!["foreignKeyColumn"]!.destinationEntity.tableName,
+            .relationships["foreignKeyColumn"]!.destinationEntity.tableName,
         totalEntity.tableName,
       );
     });
@@ -470,12 +466,12 @@ void main() {
 
     final joinEntity = model.entityForType(JoinMany);
     expect(
-      joinEntity.relationships!["left"]!.destinationEntity.instanceType ==
+      joinEntity.relationships["left"]!.destinationEntity.instanceType ==
           LeftMany,
       true,
     );
     expect(
-      joinEntity.relationships!["right"]!.destinationEntity.instanceType ==
+      joinEntity.relationships["right"]!.destinationEntity.instanceType ==
           RightMany,
       true,
     );
diff --git a/packages/core/test/db/predicate_test.dart b/packages/core/test/db/predicate_test.dart
index dff7a1a79..b97d63b99 100644
--- a/packages/core/test/db/predicate_test.dart
+++ b/packages/core/test/db/predicate_test.dart
@@ -25,10 +25,11 @@ void main() {
       expect(QueryPredicate.and([]).parameters, {});
     });
 
-    test("If null, return empty predicate", () {
-      expect(QueryPredicate.and(null).format, "");
-      expect(QueryPredicate.and(null).parameters, {});
-    });
+    // No Longer allowing null values
+    // test("If null, return empty predicate", () {
+    //   expect(QueryPredicate.and(null).format, "");
+    //   expect(QueryPredicate.and(null).parameters, {});
+    // });
 
     test("If only one element in list, return that element", () {
       final valid = QueryPredicate("x=@a", {"a": 0});
@@ -44,12 +45,13 @@ void main() {
       expect(p.parameters, valid.parameters);
     });
 
-    test("If and'ing null predicate, ignore it", () {
-      final valid = QueryPredicate("x=@a", {"a": 0});
-      final p = QueryPredicate.and([valid, null]);
-      expect(p.format, valid.format);
-      expect(p.parameters, valid.parameters);
-    });
+    // Not allowing null values
+    // test("If and'ing null predicate, ignore it", () {
+    //   final valid = QueryPredicate("x=@a", {"a": 0});
+    //   final p = QueryPredicate.and([valid, null]);
+    //   expect(p.format, valid.format);
+    //   expect(p.parameters, valid.parameters);
+    // });
 
     test("And'ing predicate with no parameters", () {
       final valid = QueryPredicate("x=y");
diff --git a/packages/postgresql/lib/src/builders/table.dart b/packages/postgresql/lib/src/builders/table.dart
index ff68a8bef..742f8d543 100644
--- a/packages/postgresql/lib/src/builders/table.dart
+++ b/packages/postgresql/lib/src/builders/table.dart
@@ -16,9 +16,8 @@ class TableBuilder implements Returnable {
     returning = ColumnBuilder.fromKeys(this, query.propertiesToFetch);
 
     columnSortBuilders = query.sortDescriptors
-            ?.map((s) => ColumnSortBuilder(this, s.key, s.order))
-            .toList() ??
-        [];
+        .map((s) => ColumnSortBuilder(this, s.key, s.order))
+        .toList();
     if (query.sortPredicate != null) {
       columnSortBuilders.add(
         ColumnSortPredicateBuilder(
@@ -55,7 +54,7 @@ class TableBuilder implements Returnable {
       }
     }
 
-    query.subQueries?.forEach((relationshipDesc, subQuery) {
+    query.subQueries.forEach((relationshipDesc, subQuery) {
       addJoinTableBuilder(
         TableBuilder(
           subQuery as PostgresQuery,
@@ -149,13 +148,11 @@ class TableBuilder implements Returnable {
 
   void finalize(Map<String, dynamic> variables) {
     final allExpressions = [
-      _manualPredicate,
+      if (_manualPredicate != null) _manualPredicate,
       ...expressionBuilders.map((c) => c.predicate)
     ];
     predicate = QueryPredicate.and(allExpressions);
-    if (predicate?.parameters != null) {
-      variables.addAll(predicate!.parameters);
-    }
+    variables.addAll(predicate!.parameters);
     returning.whereType<TableBuilder>().forEach((r) {
       r.finalize(variables);
     });
@@ -275,7 +272,7 @@ class TableBuilder implements Returnable {
       Methods that return portions of a SQL statement for this object
    */
 
-  String? get sqlTableName {
+  String get sqlTableName {
     if (tableAlias == null) {
       return entity.tableName;
     }
@@ -283,7 +280,7 @@ class TableBuilder implements Returnable {
     return "${entity.tableName} $tableAlias";
   }
 
-  String? get sqlTableReference => tableAlias ?? entity.tableName;
+  String get sqlTableReference => tableAlias ?? entity.tableName;
 
   String get sqlInnerSelect {
     final nestedJoins =
@@ -320,8 +317,8 @@ class TableBuilder implements Returnable {
       return sqlInnerSelect;
     }
 
-    final totalJoinPredicate =
-        QueryPredicate.and([joiningPredicate, predicate]);
+    final totalJoinPredicate = QueryPredicate.and(
+        [joiningPredicate, if (predicate != null) predicate!]);
     final thisJoin =
         "LEFT OUTER JOIN $sqlTableName ON ${totalJoinPredicate.format}";
 
diff --git a/packages/postgresql/lib/src/postgresql_persistent_store.dart b/packages/postgresql/lib/src/postgresql_persistent_store.dart
index 08a1219f2..4d2c08dd1 100644
--- a/packages/postgresql/lib/src/postgresql_persistent_store.dart
+++ b/packages/postgresql/lib/src/postgresql_persistent_store.dart
@@ -102,7 +102,7 @@ class PostgreSQLPersistentStore extends PersistentStore
   ///
   /// Use this property to execute raw queries on the underlying database connection.
   /// If running a transaction, this context is the transaction context.
-  Future<Session?> get executionContext => getDatabaseConnection();
+  Future<Session> get executionContext => getDatabaseConnection();
 
   /// Retrieves a connection to the database this instance connects to.
   ///
@@ -160,7 +160,7 @@ class PostgreSQLPersistentStore extends PersistentStore
     final now = DateTime.now().toUtc();
     final dbConnection = await executionContext;
     try {
-      final rows = await dbConnection!.execute(
+      final rows = await dbConnection.execute(
         Sql.named(sql),
         parameters: substitutionValues,
         timeout: timeout,
@@ -323,7 +323,7 @@ class PostgreSQLPersistentStore extends PersistentStore
     final now = DateTime.now().toUtc();
     try {
       final dbConnection = await executionContext;
-      final Result results = await dbConnection!.execute(
+      final Result results = await dbConnection.execute(
         Sql.named(formatString),
         parameters: values,
         timeout: Duration(seconds: timeoutInSeconds),
diff --git a/packages/postgresql/lib/src/postgresql_query_reduce.dart b/packages/postgresql/lib/src/postgresql_query_reduce.dart
index ec6b68c45..3dac168d6 100644
--- a/packages/postgresql/lib/src/postgresql_query_reduce.dart
+++ b/packages/postgresql/lib/src/postgresql_query_reduce.dart
@@ -6,7 +6,6 @@ import 'postgresql_persistent_store.dart';
 import 'postgresql_query.dart';
 import 'query_builder.dart';
 
-// ignore_for_file: constant_identifier_names
 enum _Reducer {
   AVG,
   COUNT,
@@ -89,7 +88,7 @@ class PostgresQueryReduce<T extends ManagedObject>
     final store = query.context.persistentStore as PostgreSQLPersistentStore;
     final connection = await store.executionContext;
     try {
-      final result = await connection!.execute(
+      final result = await connection.execute(
         Sql.named(buffer.toString()),
         parameters: builder.variables,
         queryMode: QueryMode.extended,
diff --git a/packages/postgresql/test/migration/schema_generator_sql_mapping_test.dart b/packages/postgresql/test/migration/schema_generator_sql_mapping_test.dart
index c236f3352..05c90f22e 100644
--- a/packages/postgresql/test/migration/schema_generator_sql_mapping_test.dart
+++ b/packages/postgresql/test/migration/schema_generator_sql_mapping_test.dart
@@ -350,7 +350,7 @@ void main() {
         dm.entityForType(GeneratorModel2),
         DeleteRule.cascade,
         ManagedRelationshipType.belongsTo,
-        dm.entityForType(GeneratorModel2).primaryKey,
+        dm.entityForType(GeneratorModel2).primaryKey!,
         indexed: true,
         nullable: true,
       );