Ensure exceptions from route generation are reported

Reviewed By: swarr

Differential Revision: D2631395

fb-gh-sync-id: cf59a290a4b447122c36ec20176b563a38bee630

Libraries/JavaScriptAppEngine/Initialization/InitializeJavaScriptAppEngine.js

@@ -71,6 +71,10 @@ function polyfillGlobal(name, newValue, scope=GLOBAL) {
 }
 
 function setUpErrorHandler() {
+  if (global.__fbDisableExceptionsManager) {
+    return;
+  }
+
   function handleError(e, isFatal) {
     try {
       require('ExceptionsManager').handleException(e, isFatal);