While typing in a file, NullReferenceException in ReferencesCodeLensProvider hangs language server

[daviwil]

Need a general way to catch exceptions coming from feature providers so that they don't take down the language server when they misbehave.

    System.AggregateException: One or more errors occurred. ---> System.NullReferenceException: Object reference not set to an instance of an object.
       at Microsoft.PowerShell.EditorServices.CodeLenses.ReferencesCodeLensProvider.<ResolveCodeLensAsync>d__4.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at Microsoft.PowerShell.EditorServices.CodeLenses.CodeLensFeature.<HandleCodeLensResolveRequest>d__9.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at Microsoft.PowerShell.EditorServices.Protocol.MessageProtocol.MessageDispatcher.<DispatchMessage>d__7.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at Microsoft.PowerShell.EditorServices.Protocol.MessageProtocol.ProtocolEndpoint.<ListenForMessages>d__36.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at Microsoft.PowerShell.EditorServices.Utility.AsyncContext.Start(Func`1 asyncMainFunc, ILogger logger)
       at System.Threading.Tasks.Task.Execute()

[mattmcnabb]

I'm seeing an issue where the Pester CodeLenses disappear from the document. Assuming it's due to this same issue, correct?

[daviwil]

When the Pester lenses disappear do you see any exception in the logs?

[mattmcnabb]

It appears to be the same one posted here. Tough to get an exact timestamp correlation, but it looks like the only significant error I see. There are a few other errors, but they appear to be happening around startup:

6/11/2017 1:36:47 PM [ERROR] - Method "DispatchMessage" at line 147 of C:\projects\powershelleditorservices\src\PowerShellEditorServices.Protocol\MessageProtocol\MessageDispatcher.cs

    MessageDispatcher: No handler registered for Event type 'initialized'

6/11/2017 1:36:47 PM [ERROR] - Method "DispatchMessage" at line 147 of C:\projects\powershelleditorservices\src\PowerShellEditorServices.Protocol\MessageProtocol\MessageDispatcher.cs

    MessageDispatcher: No handler registered for Event type '$/setTraceNotification'

6/11/2017 1:37:04 PM [ERROR] - Method "ListenForMessages" at line 344 of C:\projects\powershelleditorservices\src\PowerShellEditorServices.Protocol\MessageProtocol\ProtocolEndpoint.cs

    Stream terminated unexpectedly, ending MessageDispatcher loop
    
    Exception: IOException
    Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.