title: Moment timezone returning property 'preparse' of null
body: <p>While trying to parse a certain date</p>
  
  <pre><code>moment('07/07/2018', 'MM/DD/YYYY', 'Asia/Bangkok')
  </code></pre>
  
  <p>I receive the error <strong>typeError: cannot read property 'preparse' of null</strong></p>
  
  <p><a href="http://jsfiddle.net/uq99udc9/7978/" rel="nofollow noreferrer">http://jsfiddle.net/uq99udc9/7978/</a></p>