New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  openBrackets: '{{',
  closeBrackets: '}}',
  'crazy-property': 'this'
});

templates.application.hbs

<h1>Welcome to component demo</h1>
<p>
Below I try to use an non existent component with <code>{{openBrackets}}non-existent{{closeBrackets}}</code>
</p>
<hr>
{{non-existent}}
<hr>
<p>It silently fails! Why doesn't it throw an error?</p>

<p>These alternatives do throw the error</p>

<ul>
  <li>
  <code>{{openBrackets}}non-existent a="a"{{closeBrackets}}</code>
  </li>
  <li>
  <code>{{openBrackets}}component "non-existent"{{closeBrackets}}</code>
  </li>
  <li>
  <code>{{openBrackets}}#non-existent{{closeBrackets}}{{openBrackets}}/non-existent{{closeBrackets}}</code>
  </li>
 </ul>
 
 <p>The expected error is:</p>
 <blockquote>
 Uncaught Error: Assertion Failed: A helper named 'non-existent' could not be found
 </blockquote>
 
 Is it because you can do <strong>{{crazy-property}}</strong>?

twiddle.json

{
  "version": "0.4.7",
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "Handlebars": "https://cdn.jsdelivr.net/handlebarsjs/2.0.0/handlebars.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/1.9.1/ember.js"
  }
}