ember route localstorage: unable to find fixtures (ember cli)

Every time I serve my app I get the error message (unable to find fixtures). I don't want to use any fixtures, but want to store my data in localstorage. I'm using the ember-localstorage-adapter for localstorage, but get every time an error message related to the route.

My code:

Route (index.js):

import Ember from 'ember';

export default Ember.Route.extend({
  model: function() {
    return this.store.findAll('layout');
  }
});

Model (layout.js):

import DS from 'ember-data';

export default DS.Model.extend({
  positions: DS.attr('string'),
  body: DS.attr('string'),
  text: DS.attr('string')
});

Adapter (index.js):

import DS from 'ember-data';

export default DS.LSAdapter.extend({
  namespace: 'layout'
});

Serializer (index.js):

import DS from 'ember-data';

export default DS.RESTSerializer.extend({

});