Debugging with active breakpoint crashes Powershell session

[fflaten]

Prerequisites

• I have written a descriptive issue title.
• I have searched all issues to ensure it has not already been reported.
• I have read the troubleshooting guide.
• I am sure this issue is with the extension itself and does not reproduce in a standalone PowerShell instance.
• I have verified that I am using the latest version of Visual Studio Code and the PowerShell extension.

Summary

Powershell session crashes in preview extension when attempting to debug a script with active breakpoint in unsaved file. Debugging the same code in a saved file works.

Also occurs when debugging Pester tests, but was able to reproduce the same exception in this simpler demo so I believe it might be the same root cause.

PowerShell Version

Name                           Value
----                           -----
PSVersion                      7.1.3
PSEdition                      Core
GitCommitId                    7.1.3
OS                             Microsoft Windows 10.0.22000
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Visual Studio Code Version

1.62.0-insider
b3318bc0524af3d74034b8bb8a64df0ccf35549a
x64

Extension Version

ms-vscode.powershell-preview@2021.11.0

Steps to Reproduce

1. Open a new unsaved file with content $a = 1
2. Place a breakpoint on the line and launch/debug file as normal

Visuals

Repro

Exception

Logs

No response

[fflaten]

@JustinGrote Can you repro this? Would've expected you to hit this bug while troubleshooting #3655, unless it's a local problem.

[JustinGrote]

I can consistently reproduce if you:

1. Start a debug session (I use start interactive session)
2. Run a pester test

I get the same scopes issue. Doesn't happen if you don't have a debug session started.

[JustinGrote]

This particular issue (not the pester reproduction) also just happens with an unsaved file. If you save the file it works fine.

EDIT: Couldn't repro with an unsaved file either, tho the run syntax is a little strange and probably needs tweaking.

[andyleejordan]

Definitely some debugging issues to work through...

[JustinGrote]

Full stacktrace of being able to reproduce it, I'm pretty sure whatever the problem is happens before this point. I'll try to get a debug session going.

An error has occurred that was not properly handled. Additional information is shown below. The PowerShell process will exit.
Unhandled exception. System.Management.Automation.CmdletInvocationException: The scope number '3' exceeds the number of active scopes. (Parameter 'Scope')       
Actual value was 3.
 ---> System.Management.Automation.PSArgumentOutOfRangeException: The scope number '3' exceeds the number of active scopes. (Parameter 'Scope')
Actual value was 3.
   at System.Management.Automation.SessionStateInternal.GetScopeByID(Int32 scopeID)
   at System.Management.Automation.SessionStateInternal.GetScopeByID(String scopeID)
   at System.Management.Automation.SessionStateInternal.GetVariableTableAtScope(String scopeID)
   at Microsoft.PowerShell.Commands.VariableCommandBase.GetMatchingVariables(String name, String lookupScope, Boolean& wasFiltered, Boolean quiet)
   at Microsoft.PowerShell.Commands.GetVariableCommand.ProcessRecord()
   at System.Management.Automation.CommandProcessor.ProcessRecord()
   --- End of inner exception stack trace ---
   at System.Management.Automation.Runspaces.PipelineBase.Invoke(IEnumerable input)
   at System.Management.Automation.PowerShell.Worker.ConstructPipelineAndDoWork(Runspace rs, Boolean performSyncInvoke)
   at System.Management.Automation.PowerShell.CoreInvokeHelper[TInput,TOutput](PSDataCollection`1 input, PSDataCollection`1 output, PSInvocationSettings settings)
   at System.Management.Automation.PowerShell.CoreInvoke[TInput,TOutput](PSDataCollection`1 input, PSDataCollection`1 output, PSInvocationSettings settings)     
   at System.Management.Automation.PowerShell.InvokeWithDebugger(IEnumerable`1 input, IList`1 output, PSInvocationSettings settings, Boolean invokeMustRun)      
   at System.Management.Automation.ScriptDebugger.ProcessCommand(PSCommand command, PSDataCollection`1 output)
   at Microsoft.PowerShell.EditorServices.Services.PowerShell.Execution.SynchronousPowerShellTask`1.ExecuteInDebugger(CancellationToken cancellationToken) in D:\a\1\s\src\PowerShellEditorServices\Services\PowerShell\Execution\SynchronousPowerShellTask.cs:line 153
   at Microsoft.PowerShell.EditorServices.Services.PowerShell.Execution.SynchronousPowerShellTask`1.Run(CancellationToken cancellationToken) in D:\a\1\s\src\PowerShellEditorServices\Services\PowerShell\Execution\SynchronousPowerShellTask.cs:line 55
   at Microsoft.PowerShell.EditorServices.Services.PowerShell.Execution.SynchronousTask`1.ExecuteSynchronously(CancellationToken executorCancellationToken) in D:\a\1\s\src\PowerShellEditorServices\Services\PowerShell\Execution\SynchronousTask.cs:line 92
--- End of stack trace from previous location ---
   at Microsoft.PowerShell.EditorServices.Services.DebugService.FetchVariableContainerAsync(String scope, VariableContainerDetails autoVariables) in D:\a\1\s\src\PowerShellEditorServices\Services\DebugAdapter\DebugService.cs:line 690
   at Microsoft.PowerShell.EditorServices.Services.DebugService.FetchStackFramesAsync(String scriptNameOverride) in D:\a\1\s\src\PowerShellEditorServices\Services\DebugAdapter\DebugService.cs:line 818
   at Microsoft.PowerShell.EditorServices.Services.DebugService.FetchStackFramesAndVariablesAsync(String scriptNameOverride) in D:\a\1\s\src\PowerShellEditorServices\Services\DebugAdapter\DebugService.cs:line 661
   at Microsoft.PowerShell.EditorServices.Services.DebugService.OnDebuggerStopAsync(Object sender, DebuggerStopEventArgs e) in D:\a\1\s\src\PowerShellEditorServices\Services\DebugAdapter\DebugService.cs:line 920
   at System.Threading.Tasks.Task.<>c.<ThrowAsync>b__140_1(Object state)
   at System.Threading.QueueUserWorkItemCallback.Execute()
   at System.Threading.ThreadPoolWorkQueue.Dispatch()

[JustinGrote]

Looks normal up to this point, something in the _pwsh prcess setup?

[JustinGrote]

This part of the fetching of stack frames is the problem, the i loop goes to an undefined scope.

https://github.com/PowerShell/PowerShellEditorServices/blob/f825d89c5ef13423f78c5c3b68809a3daca9609f/src/PowerShellEditorServices/Services/DebugAdapter/DebugService.cs#L809-L844