ember/data issue #4986

controllers.index.js

import Ember from 'ember';

export default Ember.Controller.extend({
  
  actions: {
    
    removeBook: function(record) {
      
      record.set('author', null);
    },
    
    unloadBook: function(record) {
     
      record.unloadRecord();
    },
    
    reloadAuthors: function() {
      
      this.model.update();
    }
  }
});

mirage.config.js

export default function() {
  //window.server = this;
    this.get('/authors'),
    this.get('/books/:id')
};

mirage.factories.author.js

import { Factory } from 'ember-cli-mirage';

export default Factory.extend({

  afterCreate(authorObj) {

    authorObj.attrs.name = 'author ' + authorObj.id;
    var book = authorObj.createBook();
    book.attrs.title = 'book ' + book.id;
    book = authorObj.createBook();
    book.attrs.title = 'book ' + book.id;
  }
});

mirage.factories.book.js

import { Factory, association } from 'ember-cli-mirage';

export default Factory.extend({

  author: association()
});

mirage.models.author.js

import { Model, hasMany } from 'ember-cli-mirage';

export default Model.extend({

  books: hasMany('book')
});

mirage.models.book.js

import { Model, belongsTo } from 'ember-cli-mirage';

export default Model.extend({

  author: belongsTo('author')
});

mirage.scenarios.default.js

export default function(server) {
  // added this line because global wasn't created otherwise.
  
    server.createList('author', 2);
  
}

mirage.serializers.application.js

import { JSONAPISerializer } from 'ember-cli-mirage';

export default JSONAPISerializer.extend({
});

models.author.js

import DS from 'ember-data';

export default DS.Model.extend({

  name: DS.attr('string'),
  books: DS.hasMany('book')
});

models.book.js

import DS from 'ember-data';

export default DS.Model.extend({

  title: DS.attr('string'),
  author: DS.belongsTo('author')
});

routes.index.js

import Ember from 'ember';

export default Ember.Route.extend({

  model: function() {

    return this.store.findAll('author');
  }
});

templates.application.hbs

{{outlet}}

templates.index.hbs

<ul>
{{#each model as |author|}}
  <li>{{author.name}} <small>({{author.books.length}} books)</small>
      <ol>
        {{#each author.books as |book|}}
          <li>
          {{#if book.isLoading}}
            loading…
          {{else}}
           	<span>{{book.title}}</span>
            <small>(
           		<a href='#' {{action (action 'unloadBook' book)}}>unload</a>,
           		<a href='#' {{action (action 'removeBook' book)}}>remove</a>
            )</small>
          {{/if}}
          </li>
        {{/each}}
      </ol>
  </li>
{{/each}}
</ul>

<p>
	<button {{action (action 'reloadAuthors')}}>reload authors</button>
</p>

<p>
Switching <code>ember/data</code> from 2.12 to 2.13 in <code>twiddle.json</code> will reveal the internal error as described in <code>#4986</code> and crash the application when <u>unloading</u> a book from the store.
</p>

twiddle.json

{
  "version": "0.12.1",
  "ENV": {
    "ember-cli-mirage": {
      "enabled": true
    }
  },
  "EmberENV": {
    "FEATURES": {
      "ds-finder-include": true
    }
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.js",
    "ember": "2.12.2",
    "ember-template-compiler": "2.12.2"
  },
  "addons": {
    "ember-data": "2.13.1",
    "ember-cli-mirage": "0.3.1"
  }
}