title: Materialize: Cannot set property 'tabIndex' of null at Dropdown._makeDropdownFocusable
body: <p>I am trying to test my vuejs component via jest that contains materialize select.
  When performing a component test, I get the following error in materialize.js:</p>
  
  <pre><code>TypeError: Cannot set property 'tabIndex' of null at Dropdown._makeDropdownFocusable
  </code></pre>
  
  <p>How fix this error?</p>