Calling Get-Help with the 'ShowWindow' parameter throws an error in the integrated console

[rkeithhill]

System Details

• Operating system name and version:
  Windows 10 Enterprise Version 1607 (OS Build 14393.1066)

C:\> code -v

1.12.2
19222cdc84ce72202478ba1cec5cb557b71163de
C:\> $pseditor.EditorServicesVersion


Major  Minor  Build  Revision
-----  -----  -----  --------
1      0      0      0


C:\> code --list-extensions --show-versions

be5invis.vscode-icontheme-nomo-dark@1.3.0
christian-kohler.path-intellisense@1.4.2
eamodio.gitlens@3.4.9
eridem.vscode-postman@0.5.1
Ionide.Ionide-fsharp@2.25.12
ms-vscode.csharp@1.9.0
ms-vscode.PowerShell@1.0.0
Shan.code-settings-sync@2.7.0
Tyriar.theme-sapphire@0.2.1
C:\> $PSVersionTable


Name                           Value
----                           -----
PSVersion                      5.1.14393.1066
PSEdition                      Desktop
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
BuildVersion                   10.0.14393.1066
CLRVersion                     4.0.30319.42000
WSManStackVersion              3.0
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1


C:\>

Issue Description

Not sure if this is supposed to work, but ...

Calling Get-Help with the 'ShowWindow' parameter throws an error in the integrated console

C:\TEST> help Invoke-RestMethod -ShowWindow

Get-Help : Exception has been thrown by the target of an invocation.
At line:55 char:5
+     Get-Help @PSBoundParameters | more
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [Get-Help], TargetInvocationException
    + FullyQualifiedErrorId : System.Reflection.TargetInvocationException,Microsoft.PowerShell.Commands.GetHelpCommand
[logs.zip](https://github.com/PowerShell/vscode-powershell/files/1007246/logs.zip)

Attached Logs

logs.zip

[rkeithhill]

This is error because PSES returns null for $host.PrivateData (that's the default impl) and the PowerShell code is doing this:

https://github.com/PowerShell/PowerShell/blob/52569380c7d2bcf4060a6618e3cf81dcd320041c/src/Microsoft.PowerShell.GraphicalHost/commandHelpers/ShowCommandHelper.cs#L720-L736

Note that it is not null checking PrivateData. The fix is to simply return an empty PSObject.

BTW this is the error I see:

C:\Users\Keith> Get-Help Get-Process -ShowWindow
Get-Help : Exception has been thrown by the target of an invocation.
At line:1 char:1
+ Get-Help Get-Process -ShowWindow
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [Get-Help], TargetInvocationException
    + FullyQualifiedErrorId : System.Reflection.TargetInvocationException,Microsoft.PowerShell.Commands.GetHelpCommand

C:\Users\Keith> $error[0] | fl * -Force


PSMessageDetails      :
Exception             : System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.NullReferenceException: Object
                        reference not set to an instance of an object.
                           at Microsoft.PowerShell.Commands.ShowCommandInternal.ShowCommandHelper.GetHostWindow(PSCmdlet cmdlet)
                           at Microsoft.PowerShell.Commands.Internal.HelpWindowHelper.ShowHelpWindow(PSObject helpObj, PSCmdlet cmdlet)
                           --- End of inner exception stack trace ---
                           at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
                           at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
                           at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
                           at Microsoft.PowerShell.Commands.GetHelpCommand.WriteObjectsOrShowOnlineHelp(HelpInfo helpInfo, Boolean showFullHelp)
                           at Microsoft.PowerShell.Commands.GetHelpCommand.ProcessRecord()
                           at System.Management.Automation.CommandProcessor.ProcessRecord()
TargetObject          :
CategoryInfo          : NotSpecified: (:) [Get-Help], TargetInvocationException
FullyQualifiedErrorId : System.Reflection.TargetInvocationException,Microsoft.PowerShell.Commands.GetHelpCommand
ErrorDetails          :
InvocationInfo        : System.Management.Automation.InvocationInfo
ScriptStackTrace      : at <ScriptBlock>, <No file>: line 1
PipelineIterationInfo : {}

NOTE: this fix will NOT help with the help window attaching to the desktop and not popping to the top. That is unfortunately. But given that PSES runs in a process without a window, we'd need to pass the VSCode hwnd (on Windows only) to PSES and then we could return that hwnd when this command asks for $host.PrivateData["Window"]. Then the window would appear on top. But I'll leave that for a separate issue and PR.