title: Office.js displayDialogAsync throws internal error
body: <p>I am trying to display a dialog from an Outlook JS plugin running in Office 365's version of Outlook 2016 (recently updated, EXE version 16.0.8431.2107).</p>
  
  <p>The code I enter in the F12 debugger console is as follows:</p>
  
  <pre><code>Office.context.ui.displayDialogAsync(
      window.location.origin,
      {width: 500, height: 500},
      function(result) { 
          console.log(result) 
      }
  );
  </code></pre>
  
  <p>The result returned is</p>
  
  <pre><code>error:{
      code: 5001,
      message: "Ein interner Fehler ist aufgetreten.",
      name: "Interner Fehler"
  },
  status: "failed",
  value: undefined
  </code></pre>
  
  <p>and no dialog is opened.</p>
  
  <p>Am I overlooking some odd requirements there?</p>