Fix abnormal close JS exception

Summary:
D40660765 (3982a2c) introduced extra logging for abnormal closes. The websocked 'close' event may not be called with the event argument.

Changelog: [Internal] - Fix for undefined websocket close

Reviewed By: jacdebug, cortinico

Differential Revision: D41731339

fbshipit-source-id: 92b28dcc0d55d0e9e32b4f4321f325fb3471edcd

Libraries/Utilities/HMRClient.js

@@ -247,6 +247,7 @@ Error: ${e.message}`;
       // https://www.rfc-editor.org/rfc/rfc6455.html#section-7.4.1
       // https://www.rfc-editor.org/rfc/rfc6455.html#section-7.1.5
       const isNormalOrUnsetCloseReason =
+        closeEvent == null ||
         closeEvent.code === 1000 ||
         closeEvent.code === 1005 ||
         closeEvent.code == null;