Creating an Activity in Layout makes causes unfriendly error message

Creating an Activity in Layout makes causes unfriendly error message shown below.

I know, I know, don't do that but we could use friendlier message than this :)

System.NullReferenceException: Object reference not set to an instance of an object
  at Xamarin.AndroidDesigner.DesignerWidget.UpdateConflictsBar () [0x00012] in /Users/builder/data/lanes/monodevelop-lion-license-sync/c5f82958/source/md-addins/MonoDevelop.MonoDroid/Xamarin.AndroidDesigner/Xamarin.AndroidDesigner/DesignerWidget.cs:584 
  at Xamarin.AndroidDesigner.DesignerWidget.<HandleConflictsChanged>m__39 () [0x00002] in /Users/builder/data/lanes/monodevelop-lion-license-sync/c5f82958/source/md-addins/MonoDevelop.MonoDroid/Xamarin.AndroidDesigner/Xamarin.AndroidDesigner/DesignerWidget.cs:575 
  at Xwt.Application+<Invoke>c__AnonStorey0.<>m__A () [0x00012] in /Users/builder/data/lanes/monodevelop-lion-license-sync/c5f82958/source/monodevelop/main/external/xwt/Xwt/Xwt/Application.cs:131