Initialization Logic, Ambiguous Configurations and Update and Accept Baselines

Verified and accepted changes to ensure consistency with the expected output.

Fixed a bug where configFileParsingDiagnostics could be undefined, causing runtime errors (Cannot read properties of undefined (reading 'push')).

Added guards to ensure diagnostics arrays are always initialized before use.

Improved code resilience and prevented potential runtime errors in edge cases.

Author: RyanMyrvold

tests/baselines/reference/nestedConfigurationsWithFilesEmpty.errors.txt

@@ -0,0 +1,23 @@
+message TS6042: No actionable task. Add 'composite': true, valid 'references', or use 'tsc -b'.
+
+
+!!! message TS6042: No actionable task. Add 'composite': true, valid 'references', or use 'tsc -b'.
+==== /parent/tsconfig.json (0 errors) ====
+    {
+        "files": [],
+        "references": [{ "path": "../child" }]
+      }
+      
+      // @filename: /child/tsconfig.json
+      {
+        "compilerOptions": {
+          "declaration": true,
+          "declarationDir": "out",
+          "composite": true
+        },
+        "include": ["index.ts"]
+      }
+      
+      // @filename: /child/index.ts
+      export const childConst = "I am child!";
+      

tests/cases/compiler/compositeWithoutReferences.ts

@@ -0,0 +1,13 @@
+// @filename: /tsconfig.json
+{
+    "compilerOptions": {
+      "declaration": true,
+      "declarationDir": "out",
+      "composite": true
+    },
+    "files": []
+  }
+  
+  // @filename: /src/index.ts
+  export const compositeTest = "Composite test case";
+  

tests/cases/compiler/nestedConfigurationsWithFilesEmpty.ts

@@ -0,0 +1,19 @@
+// @filename: /parent/tsconfig.json
+{
+    "files": [],
+    "references": [{ "path": "../child" }]
+  }
+  
+  // @filename: /child/tsconfig.json
+  {
+    "compilerOptions": {
+      "declaration": true,
+      "declarationDir": "out",
+      "composite": true
+    },
+    "include": ["index.ts"]
+  }
+  
+  // @filename: /child/index.ts
+  export const childConst = "I am child!";
+  

tests/cases/compiler/noEmitBehaviorWithFilesEmpty.ts

@@ -0,0 +1,12 @@
+// @filename: /tsconfig.json
+{
+    "compilerOptions": {
+      "noEmit": true,
+      "composite": true
+    },
+    "files": []
+  }
+  
+  // @filename: /src/index.ts
+  export const noEmitTest = "This shouldn't emit";
+