DevTools: Correct ServiceDispatcher's error reporting

Change-Id: Ifd79d5b1889cbb657995efe4081ee8373664fcb3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1119115
Commit-Queue: Paul Irish <paulirish@chromium.org>
Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#641387}
diff --git a/third_party/blink/renderer/devtools/front_end/worker_service/ServiceDispatcher.js b/third_party/blink/renderer/devtools/front_end/worker_service/ServiceDispatcher.js
index a975d8e..7eb451f 100644
--- a/third_party/blink/renderer/devtools/front_end/worker_service/ServiceDispatcher.js
+++ b/third_party/blink/renderer/devtools/front_end/worker_service/ServiceDispatcher.js
@@ -38,15 +38,16 @@
    * @param {string} data
    */
   _dispatchMessageWrapped(data) {
-    const message = JSON.parse(data);
+    let message;
     try {
+      message = JSON.parse(data);
       if (!(message instanceof Object)) {
         this._sendErrorResponse(message['id'], 'Malformed message');
         return;
       }
       this._dispatchMessage(message);
     } catch (e) {
-      this._sendErrorResponse(message['id'], e.toString() + ' ' + e.stack);
+      this._sendErrorResponse(message ? message['id'] : '', e.toString() + ' ' + e.stack);
     }
   }