title: tempus-dominus doesn't detect moment import
body: <p>I know that there's a bunch of question about <code>moment</code> and <code>tempudominus-bootstrap-4</code> but most of the time it is linked to a user mistake and I didn't find reference of mine ... </p>
  
  <p>So I'm using <code>symfony</code> framework and the <code>webpack-encore</code> bundle. I want to add tempusdominus to my file <code>event.js</code> to use dateTimePicker</p>
  
  <pre class="lang-js prettyprint-override"><code>//../assets/js/app.js
  
  import $ from 'jquery';
  import 'bootstrap';
  import moment from 'moment';
  import 'tempusdominus-bootstrap-4';
  
  $(function () {
      //some datepicker
  });
  </code></pre>
  
  <p>when I refresh my page I get the following error </p>
  
  <blockquote>
    <p>Error: Tempus Dominus Bootstrap4's requires moment.js. Moment.js must be included before Tempus Dominus Bootstrap4's JavaScript.</p>
  </blockquote>
  
  <p>from here </p>
  
  <pre class="lang-js prettyprint-override"><code>// ../tempusdominus-bootstrap-4.js
  
  if (typeof moment === 'undefined') {
    throw new Error('Tempus Dominus Bootstrap4\'s requires moment.js. Moment.js must be included before Tempus Dominus Bootstrap4\'s JavaScript.');
  }
  </code></pre>
  
  <p>So apparently my moment variable is undifined. I change my app.js file to render moment in the console</p>
  
  <pre class="lang-js prettyprint-override"><code>//../assets/js/app.js
  
  import $ from 'jquery';
  import 'bootstrap';
  import moment from 'moment';
  //import 'tempusdominus-bootstrap-4';
  
  $(function () {
     console.log("type of moment = "+ typeof(moment));
  });
  </code></pre>
  
  <p>to get the following answer : </p>
  
  <blockquote>
    <p>type of moment = function</p>
  </blockquote>
  
  <p><code>moment</code> IS defined, so why tempusDominus doesn't detect it ?  </p>