return early from fixUnreachableCode if syntactic errors exists (microsoft#47463)

Author: orouz

src/services/codefixes/fixUnreachableCode.ts

@@ -5,6 +5,8 @@ namespace ts.codefix {
     registerCodeFix({
         errorCodes,
         getCodeActions(context) {
+            const syntacticDiagnostics = context.program.getSyntacticDiagnostics(context.sourceFile, context.cancellationToken);
+            if (syntacticDiagnostics.length) return;
             const changes = textChanges.ChangeTracker.with(context, t => doChange(t, context.sourceFile, context.span.start, context.span.length, context.errorCode));
             return [createCodeFixAction(fixId, changes, Diagnostics.Remove_unreachable_code, fixId, Diagnostics.Remove_all_unreachable_code)];
         },