Better error logging on event failure (#450)

* Better error logging on event failure

* Update events.js

* Update src/utils/events.js

extended serialisation

Co-authored-by: Enes Kutay SEZEN <eneskutaysezen@gmail.com>

---------

Co-authored-by: Enes Kutay SEZEN <eneskutaysezen@gmail.com>

Author: jakequade-pc

src/utils/events.js

@@ -143,7 +143,22 @@ 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 detail = '';
+    if (er && er.message) {
+      detail = ' (' + er.message + ')';
+    } else if (er !== undefined && er !== null) {
+      var serialized;
+      try {
+        serialized = JSON.stringify(er);
+      } catch (e) {
+        serialized = undefined;
+      }
+      if (typeof serialized !== 'string') {
+        serialized = Object.prototype.toString.call(er);
+      }
+      detail = ' (' + serialized + ')';
+    }
+    var err = new Error('Unhandled error.' + detail);
     err.context = er;
     throw err; // Unhandled 'error' event
   }
@@ -498,4 +513,4 @@ function eventTargetAgnosticAddListener(emitter, name, listener, flags) {
   } else {
     throw new TypeError('The "emitter" argument must be of type EventEmitter. Received type ' + typeof emitter);
   }
-}
+}