Don't report suggestion diagnostics when a parse error exists

Author: Andy Hanson

src/services/suggestionDiagnostics.ts

@@ -1,6 +1,10 @@
 /* @internal */
 namespace ts {
     export function computeSuggestionDiagnostics(sourceFile: SourceFile, program: Program, cancellationToken: CancellationToken): DiagnosticWithLocation[] {
+        if (sourceFile.parseDiagnostics.length) {
+            return emptyArray;
+        }
+
         program.getSemanticDiagnostics(sourceFile, cancellationToken);
         const diags: DiagnosticWithLocation[] = [];
 

tests/cases/fourslash/noSuggestionDiagnosticsOnParseError.ts

@@ -0,0 +1,7 @@
+/// <reference path='fourslash.ts' />
+
+// @Filename: /a.ts
+////export {};
+////const a = 1 d;
+
+verify.getSuggestionDiagnostics([]);