Feathers-mongodb bug

test.js

const adapter = require('feathers-mongodb')
const feathers = require('feathers')

class Service extends adapter.Service {
  constructor (options) {
	super(options)
	this.addedInConstructor = 'foo'
	setTimeout(() => this.testFn(), 3000)
  }

  setup (app) {
	this.app = app
	console.log('setup. app: %s, constructor: %s', !!this.app, !!this.addedInConstructor)
	console.log(this.__proto__)
  }

  testFn () {
	console.log('testFn. app: %s, constructor: %s', !!this.app, !!this.addedInConstructor)
	console.log(this.__proto__)
  }
}

const app = feathers()
const options = {}

app.use('/test', new Service(options))

app.listen(12345)

Actual result:

setup. app: true, constructor: true
{ create: null }
testFn. app: false, constructor: true
Service {}

Expected:

setup. app: true, constructor: true
Service {}
testFn. app: true, constructor: true
Service {}