Join Server returns server properly

Previously if the client was already part of a server and attempted to
accept an invite to it again, it would stall and not work correctly.

lib/channel.js

@@ -19,7 +19,7 @@ var Channel = (function () {
     _createClass(Channel, [{
         key: "equals",
         value: function equals(object) {
-            return object.id === this.id;
+            return object && object.id === this.id;
         }
     }, {
         key: "addMessage",
@@ -76,4 +76,4 @@ var Channel = (function () {
     return Channel;
 })();
 
-module.exports = Channel;
+module.exports = Channel;