Ember.js Error | Cannot read property 'some' of undefined

I'm using Ember for the front end and I am doing basic testing to see if I can properly render my data before adding components. I have two resources 'Topics' and 'Ratings' and I have added both a route and a model hook for these resources. When I type http://localhost:4200/topics, I am able to see all of the topics being rendered on the template. However, when I type http://localhost:4200/ratings, I receive an error on the console saying:

ember.debug.js:32096TypeError: Cannot read property 'some' of undefined
    at error (route.js:21)
    at Object.triggerEvent (ember.debug.js:28580)
    at Object.trigger (ember.debug.js:53473)
    at Object.Transition.trigger (ember.debug.js:53287)
    at ember.debug.js:53107
    at tryCatch (ember.debug.js:53806)
    at invokeCallback (ember.debug.js:53821)
    at publish (ember.debug.js:53789)
    at publishRejection (ember.debug.js:53724)
    at ember.debug.js:32054

Which is strange because in my rails console, I am receiving a HTTP: 200 response. Is there some error within the code of my routes? I made sure to mirror ratings similar to topics. Or is this an association issue? Both a USER and a TOPIC have many ratings. I provided snippets of my code below:

Application Route:

import Ember from 'ember';

export default Ember.Route.extend({
  auth: Ember.inject.service(),
  flashMessages: Ember.inject.service(),

  actions: {
    signOut () {
      this.get('auth').signOut()
      .then(() => this.transitionTo('sign-in'))
      .then(() => {
        this.get('flashMessages').warning('You have been signed out.');
      })
      .catch(() => {
        this.get('flashMessages')
        .danger('There was a problem. Are you sure you\'re signed-in?');
      });
      this.store.unloadAll();
    },

    error (reason) {
      let unauthorized = reason.errors.some((error) =>
        error.status === '401'
      );

      if (unauthorized) {
        this.get('flashMessages')
        .danger('You must be authenticated to access this page.');
        this.transitionTo('/sign-in');
      } else {
        this.get('flashMessages')
        .danger('There was a problem. Please try again.');
      }

      return false;
    },
  },
});

Rating Model:

import Model from 'ember-data/model';
import attr from 'ember-data/attr';
import { belongsTo } from 'ember-data/relationships';

export default Model.extend({
  score: attr('number'),
  user: belongsTo('user'),
  topic: belongsTo('topic')
});

Rating Route:

import Ember from 'ember';

export default Ember.Route.extend({
  model(params) {
    return this.get('store').findRecord('rating', params.id);
  },
});

```

Ratings Route:

import Ember from 'ember';

export default Ember.Route.extend({
  model() {
    return this.get('store').findAll('rating');
  },
});

Router:

import Ember from 'ember';
import config from './config/environment';

const Router = Ember.Router.extend({
  location: config.locationType,
});

Router.map(function () {
  this.route('sign-up');
  this.route('sign-in');
  this.route('change-password');
  this.route('users');
  this.route('topics');
  this.route('topic', { path: '/topics/:id'});
  this.route('ratings');
  this.route('rating', { path: '/ratings/:id'});
  // Custom route in topics controller that will call NYT API or generate random-show
  //topic. This is a GET request essentially
  this.route('random-show');
});

export default Router;