Better error logging on event failure

Author: jakequade-pc

src/utils/events.js

@@ -143,7 +143,7 @@ EventEmitter.prototype.emit = function emit(type) {
       throw er; // Unhandled 'error' event
     }
     // At least give some kind of context to the user
-    var err = new Error('Unhandled error.' + (er ? ' (' + er.message + ')' : ''));
+    var err = new Error('Unhandled error.' + (er && er.message ? ' (' + er.message + ')' : JSON.stringify(err)));
     err.context = er;
     throw err; // Unhandled 'error' event
   }
@@ -498,4 +498,4 @@ function eventTargetAgnosticAddListener(emitter, name, listener, flags) {
   } else {
     throw new TypeError('The "emitter" argument must be of type EventEmitter. Received type ' + typeof emitter);
   }
-}
+}