System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.VisualStudio.FSharp.Editor.FSharpLanguageService.SetupNewTextView(IVsTextView textView)
   at Microsoft.VisualStudio.LanguageServices.Implementation.LanguageService.AbstractLanguageService`2.VsCodeWindowManager.AddAdornments()
   at Microsoft.VisualStudio.Editor.Implementation.CompoundTextViewWindow.TextDocData_OnNewLanguageService(Guid& sidLangServiceID)
   at Microsoft.VisualStudio.Editor.Implementation.CompoundTextViewWindow.OnPrimaryView_FullyInitialized()
   at Microsoft.VisualStudio.Editor.Implementation.CompoundTextViewWindow.PrimaryView_TextViewHostUpdated(Object sender, EventArgs e)
   at Microsoft.VisualStudio.Editor.Implementation.SimpleTextViewWindow.Init_InitializeWpfTextView()
   at Microsoft.VisualStudio.Editor.Implementation.SimpleTextViewWindow.Init_OnActivation()
   at Microsoft.VisualStudio.Editor.Implementation.SimpleTextViewWindow.get_WpfTextViewHost()
   at Microsoft.VisualStudio.Editor.Implementation.SimpleTextViewWindow.GetData(Guid& riidKey, Object& pvtData)
   at Microsoft.VisualStudio.Editor.Implementation.VsEditorAdaptersFactoryService.GetWpfTextViewHostFromVsTextView(IVsTextView viewAdapter)
   at Microsoft.VisualStudio.Editor.Implementation.VsEditorAdaptersFactoryService.GetWpfTextViewHost(IVsTextView viewAdapter)
   at Microsoft.VisualStudio.Differencing.Package.DiffViewerCodeWindow.<>c__DisplayClass29_0.<InitializeViewer>b__0(IDifferenceTextViewModel textViewModel, ITextViewRoleSet baseRoles, IEditorOptions options, FrameworkElement& visualElement, IWpfTextViewHost& textViewHost)
   at Microsoft.VisualStudio.Text.Differencing.Implementation.DifferenceViewer.Initialize(IDifferenceBuffer differenceBuffer, CreateTextViewHostCallback createTextViewHost, IEditorOptions parentOptions)
   at Microsoft.VisualStudio.Differencing.Package.DiffViewerCodeWindow.InitializeViewer()
   at Microsoft.VisualStudio.Differencing.Package.DiffPackage.DiffFiles(String leftFile, String rightFile, IVsWindowFrame& windowFrame, UInt32 options, String caption, String tooltip, String leftLabel, String rightLabel, String inlineLabel, String roles, Boolean packageIsLoading)
   at Microsoft.VisualStudio.Differencing.Package.DiffPackage.<>c__DisplayClass17_0.<OpenComparisonWindow2>b__0()
   at Microsoft.VisualStudio.Shell.ThreadHelper.Invoke[TResult](Func`1 method)
   at Microsoft.VisualStudio.Differencing.Package.DiffPackage.OpenComparisonWindow2(String leftFile, String rightFile, String caption, String tooltip, String leftLabel, String rightLabel, String inlineLabel, String roles, UInt32 options)
   at Ankh.VS.Services.InternalDiff.RunDiff(AnkhDiffArgs args)
   at Ankh.Services.AnkhDiff.RunDiff(AnkhDiffArgs args)
   at Ankh.Commands.DiffLocalItem.OnExecute(CommandEventArgs e)
   at Ankh.Commands.CommandMapItem.OnExecute(CommandEventArgs e)
   at Ankh.Commands.CommandMapper.Execute(AnkhCommand command, CommandEventArgs e)