title: removeEditor failing on some editors
body: <p>I have some google apps script code that adds Editors to a document with no problem. However, when I run the following code I find that some of the editors are removed, and some error with the following message: "Exception: We're sorry, a server error occurred. Please wait a bit and try again."</p>
  
  <pre><code>var file = DocsList.getFileById( fid );
  var editors = file.getEditors();
  
    for ( el = 0; el &lt; editors.length ; el++ ) {
        file.removeEditor( editors[ el ] );
  }
  </code></pre>
  
  <p>Given that the editors are retrieved from the file itself, and then fail to be removed, I cannot see how to progress this, as the error message offers no help.</p>
  
  <p>Has anyone experienced similar. I cannot see any issues raised against this.</p>
  
  <p>Thanks in advance.
  Chris</p>