Browser: Identifier X has already been declared : <p>I am using ES6 with Babel in my project and I am getting an error when I declare one of my <code>const</code></p>

<pre><code>'use strict';

const APP = window.APP = window.APP || {};
const _ = window._;

APP.personalCard = (function () {

   ...

}());
</code></pre>

<p>the error</p>

<blockquote>
  <p>Uncaught TypeError: Identifier 'APP' has already been declared</p>
</blockquote>

<p>and that is the whole file, I don't have that declare anywhere else in that file. But I have declared that var in the top of the other files.</p>

<p>What do you think it should be ?</p>
