events.js:85? ? ? throw er; // Unhandled 'error' event? ? ? ? ? ? ^Error: connection closed? ? at null.<anonymous> (/Users/yuman/Documents/htdocs/Demo/mean/node_modules/mongoose/node_modules/mongodb/lib/mongodb/connection/server.js:608:24)? ? at emit (events.js:104:17)? ? at null.<anonymous> (/Users/yuman/Documents/htdocs/Demo/mean/node_modules/mongoose/node_modules/mongodb/lib/mongodb/connection/connection_pool.js:171:15)? ? at emit (events.js:110:17)? ? at Socket.<anonymous> (/Users/yuman/Documents/htdocs/Demo/mean/node_modules/mongoose/node_modules/mongodb/lib/mongodb/connection/connection.js:550:12)? ? at Socket.emit (events.js:107:17)? ? at TCP.close (net.js:485:12)源代碼是MEAN web 開發(fā)一書里的，上面貼出來的的是報(bào)錯有遇到過的請指導(dǎo)