title: Uncaught TypeError: Cannot read property 'current' of null in select2 4.0.0
body: <p>I am using select2 4.0.0 multiselect plugin. 
  I want to show existing values bind to it and when I am trying to remove the values then this particular error is coming up.</p>
  
  <blockquote>
    <p>Uncaught TypeError: Cannot read property 'current' of null </p>
  </blockquote>
  
  <p>Here is my initialization for select2</p>
  
  <pre><code>$("#multiOptions").select2({
        data:this.permissionArr,
        initSelection: (element, callback) =&gt; {
            callback([{id:1, text: 'abc'}])
        }
  });
  </code></pre>