Fix crash when serializing default export in error (#61582)

Author: andrewbranch

src/compiler/checker.ts

@@ -6156,7 +6156,6 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             },
             isOptionalParameter,
             isUndefinedIdentifierExpression(node: Identifier) {
-                Debug.assert(isExpressionNode(node));
                 return getSymbolAtLocation(node) === undefinedSymbol;
             },
             isEntityNameVisible(context, entityName, shouldComputeAliasToMakeVisible) {

tests/baselines/reference/exportAssignmentExpressionIsExpressionNode.errors.txt

@@ -0,0 +1,54 @@
+/index.ts(7,7): error TS2322: Type '{ default: { configs: { 'stage-0': PluginConfig; }; }; configs: { 'stage-0': PluginConfig; }; }' is not assignable to type 'Plugin'.
+  Types of property 'configs' are incompatible.
+    Type '{ 'stage-0': PluginConfig; }' is not assignable to type 'Record<string, { parser: string | null; }>'.
+      Property ''stage-0'' is incompatible with index signature.
+        Type 'PluginConfig' is not assignable to type '{ parser: string | null; }'.
+          Types of property 'parser' are incompatible.
+            Type 'string | null | undefined' is not assignable to type 'string | null'.
+              Type 'undefined' is not assignable to type 'string | null'.
+
+
+==== /node_modules/eslint-plugin-import-x/package.json (0 errors) ====
+    {
+      "name": "eslint-plugin-import-x",
+      "version": "1.0.0",
+      "main": "index.cjs"
+    }
+    
+==== /node_modules/eslint-plugin-import-x/index.d.cts (0 errors) ====
+    declare const eslintPluginImportX: typeof import("./lib/index.js");
+    export = eslintPluginImportX;
+    
+==== /node_modules/eslint-plugin-import-x/lib/index.d.ts (0 errors) ====
+    interface PluginConfig {
+      parser?: string | null;
+    }
+    declare const configs: {
+        'stage-0': PluginConfig;
+    };
+    declare const _default: {
+        configs: {
+            'stage-0': PluginConfig;
+        };
+    };
+    export default _default;
+    export { configs };
+    
+==== /index.ts (1 errors) ====
+    import * as pluginImportX from 'eslint-plugin-import-x'
+    
+    interface Plugin {
+      configs?: Record<string, { parser: string | null }>
+    }
+    
+    const p: Plugin = pluginImportX;
+          ~
+!!! error TS2322: Type '{ default: { configs: { 'stage-0': PluginConfig; }; }; configs: { 'stage-0': PluginConfig; }; }' is not assignable to type 'Plugin'.
+!!! error TS2322:   Types of property 'configs' are incompatible.
+!!! error TS2322:     Type '{ 'stage-0': PluginConfig; }' is not assignable to type 'Record<string, { parser: string | null; }>'.
+!!! error TS2322:       Property ''stage-0'' is incompatible with index signature.
+!!! error TS2322:         Type 'PluginConfig' is not assignable to type '{ parser: string | null; }'.
+!!! error TS2322:           Types of property 'parser' are incompatible.
+!!! error TS2322:             Type 'string | null | undefined' is not assignable to type 'string | null'.
+!!! error TS2322:               Type 'undefined' is not assignable to type 'string | null'.
+    

tests/cases/compiler/exportAssignmentExpressionIsExpressionNode.ts

@@ -0,0 +1,39 @@
+// @strict: true
+// @module: nodenext
+// @noEmit: true
+// @noTypesAndSymbols: true
+
+// @Filename: /node_modules/eslint-plugin-import-x/package.json
+{
+  "name": "eslint-plugin-import-x",
+  "version": "1.0.0",
+  "main": "index.cjs"
+}
+
+// @Filename: /node_modules/eslint-plugin-import-x/index.d.cts
+declare const eslintPluginImportX: typeof import("./lib/index.js");
+export = eslintPluginImportX;
+
+// @Filename: /node_modules/eslint-plugin-import-x/lib/index.d.ts
+interface PluginConfig {
+  parser?: string | null;
+}
+declare const configs: {
+    'stage-0': PluginConfig;
+};
+declare const _default: {
+    configs: {
+        'stage-0': PluginConfig;
+    };
+};
+export default _default;
+export { configs };
+
+// @Filename: /index.ts
+import * as pluginImportX from 'eslint-plugin-import-x'
+
+interface Plugin {
+  configs?: Record<string, { parser: string | null }>
+}
+
+const p: Plugin = pluginImportX;