Check for a module sysmbol existing before calling getReferencedSymbolsForModule

Author: mhegazy

src/services/findAllReferences.ts

@@ -234,7 +234,8 @@ namespace ts.FindAllReferences.Core {
     export function getReferencedSymbolsForNode(position: number, node: Node, program: Program, sourceFiles: ReadonlyArray<SourceFile>, cancellationToken: CancellationToken, options: Options = {}, sourceFilesSet: ReadonlyMap<true> = arrayToSet(sourceFiles, f => f.fileName)): SymbolAndEntries[] | undefined {
         if (isSourceFile(node)) {
             const reference = GoToDefinition.getReferenceAtPosition(node, position, program);
-            return reference && getReferencedSymbolsForModule(program, program.getTypeChecker().getMergedSymbol(reference.file.symbol), /*excludeImportTypeOfExportEquals*/ false, sourceFiles, sourceFilesSet);
+            const moduleSymbol = reference && program.getTypeChecker().getMergedSymbol(reference.file.symbol);
+            return moduleSymbol && getReferencedSymbolsForModule(program, moduleSymbol, /*excludeImportTypeOfExportEquals*/ false, sourceFiles, sourceFilesSet);
         }
 
         if (!options.implementations) {