Simple Ember Data Issue with Mirage

I have some experience with Ember.js, and am now going through creating a new project, with Mirage to stub the data for now.

I'm going through the Ember.js Tutorial step by step but keep getting this error when querying for records:

Encountered a resource object with an undefined type (resolved resource using DS.JSONAPISerializer)

I do realize that a similar question has been asked, but it did not include the Mirage addon, and I also went through all of the techniques answered in that question.

---

mirage/config.js

export default function() {
  this.namespace = '/api'

  this.get('/todos', function() {
    return {
      data: [
        {
          text: 'Bring in garbage cans',
          completed: false,
          timesViewed: 3
        },
        {
          text: 'Look at the plants',
          completed: false,
          timesViewed: 0
        }
      ]
    }
  })
}

---

app/models/todo.js

import DS from 'ember-data';

export default DS.Model.extend({
    text: DS.attr(),
    completed: DS.attr(),
    timesViewed: DS.attr()
});

---

app/routes/index.js

import Route from '@ember/routing/route';

export default Route.extend({
    model() {
        return this.store.findAll('todo')
    }
});

---

app/adapters/application.js

import DS from 'ember-data';

export default DS.JSONAPIAdapter.extend({
    namespace: 'api'
});

---

I've been formatting the response from Mirage in all kinds of ways, even doing the double quotes on keys, but that shouldn't be necessary since I believe mirage serializes it.

Any help on what I'm missing here is appreciated.