title: Cannot use 'in' operator to search for '_id' in
body: <p>I'm trying to get an existing user document using mongoose with express but I only get this:</p>
  
  <pre><code>/webroot/api.domain.com/production/node_modules/mongoose/lib/document.js:162
        if (obj &amp;&amp; '_id' in obj) continue;
                            ^
  TypeError: Cannot use 'in' operator to search for '_id' in Account
      at model.Document._buildDoc (/webroot/api.domain.com/production/node_modules/mongoose/lib/document.js:162:27)
      at model.Document (/webroot/api.domain.com/production/node_modules/mongoose/lib/document.js:67:20)
      at model.Model (/webroot/api.domain.com/production/node_modules/mongoose/lib/model.js:33:12)
      at new model (/webroot/api.domain.com/production/node_modules/mongoose/lib/model.js:1663:11)
      at Object.model (/webroot/api.domain.com/production/node_modules/mongoose/lib/model.js:1662:14)
      at Object.findOrCreateOneForTwitter (/webroot/api.domain.com/production/models/account.coffee:60:17)
      at module.exports.callback.error (/webroot/api.domain.com/production/endpoints/twitter.coffee:67:34)
      at Twitter.get (/webroot/api.domain.com/production/node_modules/ntwitter/lib/twitter.js:85:7)
      at passBackControl (/webroot/api.domain.com/production/node_modules/oauth/lib/oauth.js:361:11)
      at IncomingMessage.exports.OAuth._performSecureRequest.request.on.callbackCalled (/webroot/api.domain.com/production/node_modules/oauth/lib/oauth.js:380:9)
  </code></pre>
  
  <p>Is there any known fix for that? Thanks.</p>