http://stackoverflow.com/questions/39083962/ember-application-only-shows-blank-page-on-errors-cannot-render-error-action

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

router.js

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

const Router = Ember.Router.extend({
  location: 'none',
  rootURL: config.rootURL
});

Router.map(function() {
 this.route('reports');

});

export default Router;

routes.application.js

import Ember from 'ember';
const {RSVP} = Ember;
export default Ember.Route.extend({
  model(){
    return new RSVP.Promise(function(resolve,reject) {
       reject("Error");
    });
  }
});

routes.reports.js

import Ember from 'ember';
const {RSVP} = Ember;
export default Ember.Route.extend({
  model(){
    return new RSVP.Promise(function(resolve,reject) {
       reject("Error");
    });
  }
});

templates.application-error.hbs

application-error

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>

templates.error.hbs

Error.hbs

templates.reports.hbs

Reports.hbs

twiddle.json

{
  "version": "0.10.4",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.7.0",
    "ember-data": "2.7.0",
    "ember-template-compiler": "2.7.0"
  },
  "addons": {}
}