title: No item with the given ID could be found, or you do not have permission to access it
body: <p>I have an add-on which requires access to various Google services, and requests the following access when initially loaded:</p>
  
  <p><a href="https://i.stack.imgur.com/LN5kJ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/LN5kJ.png" alt="enter image description here"></a></p>
  
  <p>I also have a webapp which runs as me (the same google account as the add-on) and can be accessed by anyone including anonymous.  The webapp trys to access a form which I believe I should already have access to. </p>
  
  <p>Webapp:</p>
  
  <pre><code>function doGet(){
    var form = FormApp.openById('');
    var formId = form.getId();
    var items = form.getItems();
    return ContentService.createTextOutput("Form contains "+items.length+"items.");
  }
  </code></pre>
  
  <p>Error:</p>
  
  <blockquote>
    <p>No item with the given ID could be found, or you do not have
    permission to access it.</p>
  </blockquote>
  
  <p><strong>Question:</strong></p>
  
  <p>When the add-on initially requests access to the user's Drive, does this give access to the <em>add-on only</em> or to the <em>developers google account</em>?</p>