[VS] R language service throws exception when guest joins, repeatedly displays errors on newline

[Chuxel]

While the behavior here is like a bug and should be resolved, full language service support has not yet been implemented for R.

Product and Version: Visual Studio 2017 Preview (15.6 Preview 3)
OS Version: Windows 10 Enterprise 64-bit
Live Share Extension Version: 0.2.64
Target Platform or Language: R projects

Steps to Reproduce / Scenario:

1. [Host] Create a new R project
2. [Host] Open Script.R and add print("1234") a few times
3. [Host] Share
4. [Guest] Join
5. [Guest] After clicking ok on the exception dialog that appears, hit enter in the file

Expected: Language services come online, no exceptions
Actual: Dialog indicating an error occurred appears on join. Each newline results in a dialog stating "Object reference set to an instance of an object."

ActivityLog.xml shows:

862 2018/01/31 23:35:51.873 Error Microsoft.VisualStudio.CommonIDE.ExtensibilityHosting.VsShellComponentModelHost A MEF Component threw an exception at runtime: Microsoft.VisualStudio.Composition.CompositionFailedException: An exception was thrown while initializing part "Microsoft.VisualStudio.R.Package.Commands.R.VsRTextViewConnectionListener". ---> System.NullReferenceException: Object reference not set to an instance of an object. at Microsoft.Languages.Editor.Controllers.Views.TextViewConnectionListener..ctor(IServiceContainer services) at Microsoft.VisualStudio.R.Package.Commands.R.VsRTextViewConnectionListener..ctor(ICoreShell coreShell) --- End of inner exception stack trace --- at Microsoft.VisualStudio.Composition.RuntimeExportProviderFactory.RuntimeExportProvider.RuntimePartLifecycleTracker.CreateValue() at Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.Create() at Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.MoveNext(PartLifecycleState nextState) at Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.GetValueReadyToExpose() at Microsoft.VisualStudio.Composition.RuntimeExportProviderFactory.RuntimeExportProvider.<>c__DisplayClass15_0.<GetExportedValueHelper>b__0() --- End of stack trace from previous location where exception was thrown --- at Microsoft.VisualStudio.Composition.RuntimeExportProviderFactory.RuntimeExportProvider.<>c__DisplayClass15_0.<GetExportedValueHelper>b__0() at Microsoft.VisualStudio.Composition.DelegateServices.<>c__DisplayClass2_0`1.<As>b__0() at System.Lazy`1.CreateValue() at System.Lazy`1.LazyInitValue() at System.Lazy`1.get_Value() at Microsoft.VisualStudio.Text.Utilities.GuardedOperations.InstantiateExtension[TExtension,TMetadata](Object errorSource, Lazy`2 provider) --- End of stack trace from previous location where exception was thrown --- at Microsoft.VisualStudio.Telemetry.WindowsErrorReporting.WatsonReport.GetClrWatsonExceptionInfo(Exception exceptionObject) --- End of stack trace from previous location where exception was thrown --- at Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.GetValueReadyToExpose() at Microsoft.VisualStudio.Composition.RuntimeExportProviderFactory.RuntimeExportProvider.<>c__DisplayClass15_0.<GetExportedValueHelper>b__0() 863 2018/01/31 23:35:56.035 Error Editor or Editor Extension Microsoft.VisualStudio.Composition.CompositionFailedException: An exception was thrown while initializing part "Microsoft.VisualStudio.R.Package.Commands.R.VsRTextViewConnectionListener". ---> System.NullReferenceException: Object reference not set to an instance of an object. at Microsoft.Languages.Editor.Controllers.Views.TextViewConnectionListener..ctor(IServiceContainer services) at Microsoft.VisualStudio.R.Package.Commands.R.VsRTextViewConnectionListener..ctor(ICoreShell coreShell) --- End of inner exception stack trace --- at Microsoft.VisualStudio.Composition.RuntimeExportProviderFactory.RuntimeExportProvider.RuntimePartLifecycleTracker.CreateValue() at Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.Create() at Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.MoveNext(PartLifecycleState nextState) at Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.GetValueReadyToExpose() at Microsoft.VisualStudio.Composition.RuntimeExportProviderFactory.RuntimeExportProvider.<>c__DisplayClass15_0.<GetExportedValueHelper>b__0() --- End of stack trace from previous location where exception was thrown --- at Microsoft.VisualStudio.Composition.RuntimeExportProviderFactory.RuntimeExportProvider.<>c__DisplayClass15_0.<GetExportedValueHelper>b__0() at Microsoft.VisualStudio.Composition.DelegateServices.<>c__DisplayClass2_0`1.<As>b__0() at System.Lazy`1.CreateValue() at System.Lazy`1.LazyInitValue() at System.Lazy`1.get_Value() at Microsoft.VisualStudio.Text.Utilities.GuardedOperations.InstantiateExtension[TExtension,TMetadata](Object errorSource, Lazy`2 provider) --- End of stack trace from previous location where exception was thrown --- at Microsoft.VisualStudio.Telemetry.WindowsErrorReporting.WatsonReport.GetClrWatsonExceptionInfo(Exception exceptionObject) --- End of stack trace from previous location where exception was thrown --- at Microsoft.VisualStudio.Composition.ExportProvider.PartLifecycleTracker.GetValueReadyToExpose() at Microsoft.VisualStudio.Composition.RuntimeExportProviderFactory.RuntimeExportProvider.<>c__DisplayClass15_0.<GetExportedValueHelper>b__0() --- End of stack trace from previous location where exception was thrown --- at Microsoft.VisualStudio.Composition.RuntimeExportProviderFactory.RuntimeExportProvider.<>c__DisplayClass15_0.<GetExportedValueHelper>b__0() at Microsoft.VisualStudio.Composition.DelegateServices.<>c__DisplayClass2_0`1.<As>b__0() at System.Lazy`1.CreateValue() at System.Lazy`1.LazyInitValue() at System.Lazy`1.get_Value() at Microsoft.VisualStudio.Text.Utilities.GuardedOperations.InstantiateExtension[TExtension,TMetadata](Object errorSource, Lazy`2 provider) --- End of stack trace from previous location where exception was thrown --- at Microsoft.VisualStudio.Telemetry.WindowsErrorReporting.WatsonReport.GetClrWatsonExceptionInfo(Exception exceptionObject)

[lostintangent]

This issue no longer repros.