照着nodejs实战 书中的用nodejs + angularjs + socket + mongodb 弄得一个聊天程序，不知道怎么回事出现这个问题，是session的原因？

d:\Coding\My sites T\绉掑井璇惧爞瀛︿範\demo\nodeT\node API\mean_talk\node_modul
es\connect\lib\utils.js:232 **return 0 == str.indexOf(‘s:’) ** ^ **TypeError: Cannot call method ‘indexOf’ of undefined\n ** at exports.parseSignedCookie (d:\Coding\My sites T\绉掑井璇惧爞瀛︿範\demo\n odeT\node API\mean_talk\node_modules\connect\lib\utils.js:232:19) at messages (d:\Coding\My sites T\绉掑井璇惧爞瀛︿範\demo\nodeT\node API\mea n_talk\app.js:86:16) at Array.0 (d:\Coding\My sites T\绉掑井璇惧爞瀛︿範\demo\nodeT\node API\mean _talk\node_modules\socket.io\lib\index.js:117:7) at run (d:\Coding\My sites T\绉掑井璇惧爞瀛︿範\demo\nodeT\node API\mean_tal k\node_modules\socket.io\lib\namespace.js:114:11) at Namespace.run (d:\Coding\My sites T\绉掑井璇惧爞瀛︿範\demo\nodeT\node AP I\mean_talk\node_modules\socket.io\lib\namespace.js:126:3) at Namespace.add (d:\Coding\My sites T\绉掑井璇惧爞瀛︿範\demo\nodeT\node AP I\mean_talk\node_modules\socket.io\lib\namespace.js:155:8) at Client.connect (d:\Coding\My sites T\绉掑井璇惧爞瀛︿範\demo\nodeT\node A\n PI\mean_talk\node_modules\socket.io\lib\client.js:67:20) at Server.onconnection (d:\Coding\My sites T\绉掑井璇惧爞瀛︿範\demo\nodeT\n ode API\mean_talk\node_modules\socket.io\lib\index.js:307:10) at Server.EventEmitter.emit (events.js:95:17) at Server.handshake (d:\Coding\My sites T\绉掑井璇惧爞瀛︿範\demo\nodeT\node API\mean_talk\node_modules\socket.io\node_modules\engine.io\lib\server.js:250:8 )