PR Summary

StopUpstreamCommandsException is a special exception used by cmdlets to tell PowerShell to stop upstream commands as it doesn't need any additional input. For example: "1,2,3 | select-object -first 1" should stop the first part of the pipeline after select-object received 1 object as the request has been fulfilled. However, if you use 1,2,3 | select-object -first 1 -errorvariable err, the internal exception (which is handled) is put into the $err variable (although $error it not populated). This means that scripts may treat this as an error or special case this System error and throwing it away.

The fix is in the code where the engine populates -ErrorVariable to discard StopUpstreamCommandsException.

I don't believe this is a breaking change as anyone working around this by throwing away that specific error (because select-object actually succeeded) won't be impacted by this change.

PR Context

Fix #9185

PR Checklist

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• Breaking changes
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  • Experimental feature(s) needed
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• User-facing changes
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  • Documentation needed
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  • I have considered the user experience from a tooling perspective and don't believe tooling will be impacted.
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    • Impact on PowerShell Editor Services which is used in the PowerShell extension for VSCode (which runs in a different PS Host).
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    • Impact on PSScriptAnalyzer (which provides linting & formatting in the editor extensions).
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