TypeError: Cannot read property 'length' of undefined

[peterzyn]

✔ Express server listening on port 3001 in development mode

/Users/peter/Desktop/stu/express4-bootstrap-starter/node_modules/mongoose/node_modules/mongodb/lib/mongodb/connection/base.js:246 throw message;
^ TypeError: Cannot read property 'length' of undefined at processResults (/Users/peter/Desktop/stu/express4-bootstrap-starter/node_modules/mongoose/node_modules/mongodb/lib/mongodb/db.js:1581:31) at /Users/peter/Desktop/stu/express4-bootstrap-starter/node_modules/mongoose/node_modules/mongodb/lib/mongodb/db.js:1619:20 at /Users/peter/Desktop/stu/express4-bootstrap-starter/node_modules/mongoose/node_modules/mongodb/lib/mongodb/db.js:1157:7 at /Users/peter/Desktop/stu/express4-bootstrap-starter/node_modules/mongoose/node_modules/mongodb/lib/mongodb/db.js:1890:9 at Server.Base._callHandler (/Users/peter/Desktop/stu/express4-bootstrap-starter/node_modules/mongoose/node_modules/mongodb/lib/mongodb/connection/base.js:448:41) at /Users/peter/Desktop/stu/express4-bootstrap-starter/node_modules/mongoose/node_modules/mongodb/lib/mongodb/connection/server.js:481:18 at MongoReply.parseBody (/Users/peter/Desktop/stu/express4-bootstrap-starter/node_modules/mongoose/node_modules/mongodb/lib/mongodb/responses/mongo_reply.js:68:5) at null. (/Users/peter/Desktop/stu/express4-bootstrap-starter/node_modules/mongoose/node_modules/mongodb/lib/mongodb/connection/server.js:439:20) at EventEmitter.emit (events.js:95:17) at null. (/Users/peter/Desktop/stu/express4-bootstrap-starter/node_modules/mongoose/node_modules/mongodb/lib/mongodb/connection/connection_pool.js:201:13)