Update server.js

fix bug

lib/server.js

@@ -21,6 +21,7 @@ app._initializeWSS = function(server) {
   this._wss = new WebSocketServer({ path: path, server: server});
 
   this._wss.on('connection', function(socket, req) {
+    if(!req.url) return;
     var query = url.parse(req.url, true).query;
     var id = query.id;
     var token = query.token;