title: Forge viewer Document.load throws exception on mobile devices
body: <p>We are using Forge viewer version 3.2.x.</p>
  
  <p>For <strong><em>Autodesk.Viewing.Document</em></strong> the function <strong><em>load(documentId,onSuccessCallback,onErrorCallback,accessControlProperties)</em></strong> the parameter <em>accessControlProperties</em> is listed as required (see <a href="https://developer.autodesk.com/en/docs/viewer/v2/reference/javascript/document/" rel="nofollow noreferrer">Autodesk Forge Documentation</a>). Not providing this parameter still works on Chrome / Firefox, but I discovered that missing the parameter causes problems on mobile devices. However, for this parameter there seems to be no example or specification available.</p>
  
  <p>Maybe the problem is not the missing parameter itself but something else...? Getting the following exception in browser console:</p>
  
  <pre><code>Uncaught TypeError: Cannot read property 'id' of null
  at PinchRecognizer.recognizeWith (viewer3D.js?v=3.2.*:2300)
  at Array.forEach (&lt;anonymous&gt;)
  at each (viewer3D.js?v=3.2.*:923)
  at invokeArrayArg (viewer3D.js?v=3.2.*:903)
  at PinchRecognizer.recognizeWith (viewer3D.js?v=3.2.*:2294)
  at new Autodesk.Viewing.GestureHandler (viewer3D.js?v=3.2.*:16042)
  at GuiViewer3D.Viewer3D.createControls (viewer3D.js?v=3.2.*:44685)
  at GuiViewer3D.Viewer3D.initialize (viewer3D.js?v=3.2.*:44758)
  at GuiViewer3D.initialize (viewer3D.js?v=3.2.*:50852)
  at GuiViewer3D.Viewer3D.start (viewer3D.js?v=3.2.*:44555)
  </code></pre>
  
  <p>Using <em>Viewer.loadDocument(documentId,onDocumentLoad,onLoadFailed,accessControlProperties)</em> is not an option, because we must load multiple models into the viewer.</p>