Null dereference when debugging Pester tests

[andyleejordan]

@andschwa Sadly I just hit this in Pester on v2022.1.0 while debugging. I'll try to get a better repro together.

EDIT: Only seems to trigger in debug, non-debug it doesn't happen.

An error occurred while running the REPL loop:
System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.PowerShell.EditorServices.Services.PowerShell.Debugging.PowerShellDebugContext.ProcessDebuggerResult(DebuggerCommandResults debuggerResult) in D:\a\1\s\src\PowerShellEditorServices\Services\PowerShell\Debugging\PowerShellDebugContext.cs:line 154
   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 196
   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 104
--- End of stack trace from previous location ---
   at Microsoft.PowerShell.EditorServices.Services.PowerShell.Execution.SynchronousTask`1.get_Result() in D:\a\1\s\src\PowerShellEditorServices\Services\PowerShell\Execution\SynchronousTask.cs:line 60
   at Microsoft.PowerShell.EditorServices.Services.PowerShell.Execution.SynchronousTask`1.ExecuteAndGetResult(CancellationToken cancellationToken) in D:\a\1\s\src\PowerShellEditorServices\Services\PowerShell\Execution\SynchronousTask.cs:line 109
   at Microsoft.PowerShell.EditorServices.Services.PowerShell.Host.PsesInternalHost.InvokePSCommand[TResult](PSCommand psCommand, PowerShellExecutionOptions executionOptions, CancellationToken cancellationToken) in D:\a\1\s\src\PowerShellEditorServices\Services\PowerShell\Host\PsesInternalHost.cs:line 371
   at Microsoft.PowerShell.EditorServices.Services.PowerShell.Host.PsesInternalHost.InvokePSCommand(PSCommand psCommand, PowerShellExecutionOptions executionOptions, CancellationToken cancellationToken) in D:\a\1\s\src\PowerShellEditorServices\Services\PowerShell\Host\PsesInternalHost.cs:line 375
   at Microsoft.PowerShell.EditorServices.Services.PowerShell.Host.PsesInternalHost.InvokeInput(String input, CancellationToken cancellationToken) in D:\a\1\s\src\PowerShellEditorServices\Services\PowerShell\Host\PsesInternalHost.cs:line 678
   at Microsoft.PowerShell.EditorServices.Services.PowerShell.Host.PsesInternalHost.DoOneRepl(CancellationToken cancellationToken) in D:\a\1\s\src\PowerShellEditorServices\Services\PowerShell\Host\PsesInternalHost.cs:line 640

Script Used

Describe 'ConvertTo-ReliefJetPST' {
    BeforeAll {
        Import-Module $PSScriptRoot/PSTMigration.psm1 -Force
        $SCRIPT:Mocks = Resolve-Path (Join-Path $PSScriptRoot $PSTMigration.Mocks)
    }
    It 'Folder with MSG files, different destination' {

        $MockSource = Join-Path $Mocks 'FolderWithMsgFile'
        $MockSource
        | ConvertTo-ReliefJetPST -Destination 'TestDrive:/'
    }
}

Originally posted by @JustinGrote in #1642 (comment)