Will-destroy-element-reproduction

The basic problem

This is a reproduction of an Ember issue.

You used to be able to set properties in willDestroyElement and have them work before Ember 2.8. This mostly works, except when you have an {{#if}} helper in your template. On Ember 2.8.0, this results in an error:

TypeError: Cannot read property 'push' of null
    at cleanupRenderNode (http://localhost:7357/assets/vendor.js:20703:47)
    at destroyNode (http://localhost:7357/assets/vendor.js:57340:9)
    at Object.visitChildren (http://localhost:7357/assets/vendor.js:56988:7)
    at Object.clearMorph (http://localhost:7357/assets/vendor.js:57357:29)
    at RenderResult.destroy (http://localhost:7357/assets/vendor.js:56666:32)
    at Renderer.remove (http://localhost:7357/assets/vendor.js:25025:18)
    at Object.destroy (http://localhost:7357/assets/vendor.js:54237:21)
    at Class.destroy (http://localhost:7357/assets/vendor.js:53203:26)
    at Class.superWrapper [as destroy] (http://localhost:7357/assets/vendor.js:35186:22)
    at Object.run (http://localhost:7357/assets/vendor.js:10681:25)

This error mainly seems to occur in tests when components are being torn down.

Component definition:

import Ember from 'ember';

export default Ember.Component.extend({
  showWelcome: true,

  willDestroyElement() {
    Ember.run(() => {
      this.set('showWelcome', false);
    });
    this._super(...arguments);
  }
});

Component Template:

{{#if showWelcome}}
  Welcome!
{{/if}}

Interestingly enough, this error does not occur if you have an {{else}} case, like so:

{{#if showWelcome}}
  Welcome!
{{else}}
  Goodbye
{{/if}}

Prerequisites

You will need the following things properly installed on your computer.

Installation

git clone <repository-url> this repository
cd will-destroy-element-reproduction
npm install
bower install

Running / Development

ember serve
Visit your app at http://localhost:4200.

Code Generators

Make use of the many generators for code, try ember help generate for more details

Running Tests

ember test
ember test --server

Building

ember build (development)
ember build --environment production (production)

Deploying

Specify what it takes to deploy your app.

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