Fixed realtime.js finishConnection user might be undefined issue

Author: jackycute

lib/realtime.js

@@ -268,6 +268,7 @@ var isDisconnectBusy = false;
 var disconnectSocketQueue = [];
 
 function finishConnection(socket, note, user) {
+    if (!socket || !note || !user) return;
     note.users[socket.id] = user;
     note.socks.push(socket);
     note.server.addClient(socket);