heroku err

2016-03-17T13:42:55.657671+00:00 app[web.1]: Thu, 17 Mar 2016 13:42:55 GMT body-parser deprecated undefined extended: provide extended option at node_modules/body-parser/index.js:105:29
2016-03-17T13:42:56.277987+00:00 app[web.1]: Express server listening on port 48459
2016-03-17T13:42:56.537555+00:00 app[web.1]: /app/node_modules/mongoosastic/lib/serialize.js:9
2016-03-17T13:42:56.537567+00:00 app[web.1]: TypeError: Cannot read property 'title' of null
2016-03-17T13:42:56.537564+00:00 app[web.1]:         val = serialize.call(object, object[field], mappingData.properties[field]);
2016-03-17T13:42:56.537566+00:00 app[web.1]:                                            ^
2016-03-17T13:42:56.537567+00:00 app[web.1]:
2016-03-17T13:42:56.537568+00:00 app[web.1]:     at _serializeObject (/app/node_modules/mongoosastic/lib/serialize.js:9:44)
2016-03-17T13:42:56.537572+00:00 app[web.1]:     at model.schemaIndex [as index] (/app/node_modules/mongoosastic/lib/mongoosastic.js:306:19)
2016-03-17T13:42:56.537569+00:00 app[web.1]:     at /app/node_modules/mongoosastic/lib/serialize.js:21:34
2016-03-17T13:42:56.537571+00:00 app[web.1]:     at _serializeObject (/app/node_modules/mongoosastic/lib/serialize.js:9:25)
2016-03-17T13:42:56.537569+00:00 app[web.1]:     at Array.map (native)
2016-03-17T13:42:56.537572+00:00 app[web.1]:     at model.postSave (/app/node_modules/mongoosastic/lib/mongoosastic.js:626:13)
2016-03-17T13:42:56.537570+00:00 app[web.1]:     at model.serialize (/app/node_modules/mongoosastic/lib/serialize.js:21:20)
2016-03-17T13:42:56.537573+00:00 app[web.1]:     at EventEmitter.<anonymous> (/app/node_modules/mongoose/lib/schema.js:870:17)
2016-03-17T13:42:56.537586+00:00 app[web.1]:     at model.Document.(anonymous function) [as emit] (/app/node_modules/mongoose/lib/document.js:88:44)
2016-03-17T13:42:56.537571+00:00 app[web.1]:     at serialize (/app/node_modules/mongoosastic/lib/serialize.js:24:12)
2016-03-17T13:42:56.537574+00:00 app[web.1]:     at emitTwo (events.js:105:20)
2016-03-17T13:42:56.537588+00:00 app[web.1]:     at model.Model.$__save (/app/node_modules/mongoose/lib/model.js:186:9)
2016-03-17T13:42:56.537587+00:00 app[web.1]:     at /app/node_modules/mongoose/lib/model.js:226:11
2016-03-17T13:42:56.537588+00:00 app[web.1]:     at model.Model.$__handleSave (/app/node_modules/mongoose/lib/model.js:171:7)
2016-03-17T13:42:56.537574+00:00 app[web.1]:     at EventEmitter.emit (events.js:185:7)
2016-03-17T13:42:56.537592+00:00 app[web.1]:     at /app/node_modules/mongoose/lib/model.js:285:11
2016-03-17T13:42:57.224771+00:00 heroku[web.1]: Process exited with status 1
2016-03-17T13:42:57.256352+00:00 heroku[web.1]: State changed from starting to crashed