adding a check so that websocket method in notif pushing isn't called if the socket server isn't initialised

src/notifications.js

@@ -197,9 +197,11 @@ var async = require('async'),
 			plugins.fireHook('action:notification.pushed', {notification: notification, uids: uids});
 
 			var websockets = require('./socket.io');
+			if (websockets.server) {
 				for(var i=0; i<uids.length; ++i) {
 					websockets.in('uid_' + uids[i]).emit('event:new_notification', notification);
 				}
+			}
 
 			callback();
 		});