got to page 15, and added , User = require('./models/User.js'); but when i try to start the app im getting the following error. any ideas on what i might be doing wrong?

Code javascript:
/authentication/node_modules/mongoose/lib/utils.js:413
        throw err;
              ^
Error: Uncaught, unspecified 'error' event.
    at NativeConnection.EventEmitter.emit (events.js:73:15)
    at Model.init (/authentication/node_modules/mongoose/lib/model.js:554:31)
    at exports.tick (/authentication/node_modules/mongoose/lib/utils.js:408:16)
    at Db.ensureIndex (/authentication/node_modules/mongoose/node_modules/mongodb/lib/mongodb/db.js:1066:28)
    at Db.indexInformation (/authentication/node_modules/mongoose/node_modules/mongodb/lib/mongodb/db.js:1200:28)
    at Cursor.toArray (/authentication/node_modules/mongoose/node_modules/mongodb/lib/mongodb/cursor.js:124:30)
    at Cursor.each (/authentication/node_modules/mongoose/node_modules/mongodb/lib/mongodb/cursor.js:166:32)
    at Cursor.nextObject.self.queryRun (/authentication/node_modules/mongoose/node_modules/mongodb/lib/mongodb/cursor.js:441:39)
    at Cursor.close (/authentication/node_modules/mongoose/node_modules/mongodb/lib/mongodb/cursor.js:687:5)
    at Cursor.nextObject.commandHandler (/authentication/node_modules/mongoose/node_modules/mongodb/lib/mongodb/cursor.js:441:21)

  1. if i comment out in /authentication/models/User.js, the line var MyUser = db.mongoose.model('User', UserSchema); then the app starts without throwing an error.
  2. when i change /authentication/node_modules/mongoose/node_modules/mongodb/lib/mongodb/utils.js line 413 to console.log(err) i get : [Error: Uncaught, unspecified 'error' event.]
  3. when i change /authentication/node_modules/mongoose/node_modules/mongodb/lib/mongodb/utils.js line 413 to console.log(callback) i get : [function]
  4. when i add to /authentication/node_modules/mongoose/node_modules/mongodb/lib/mongodb/model.js 554, console.log(err); i get an error which i believe is the problem - unauthorized db:nodemarket ns:nodemarket.system.indexes lock type:0 client: xxx.xxx.xxx.xxx (my ip address)
    1. how do i fix that?
    2. why doesnt node show this error instead of Uncaught, unspecified 'error' event?