Allow writing null to Function output

[AnatoliB]

Allow writing null to Function output by making the InputObject parameter of Trace-PipelineObject optional (which enables passing $null).

Resolves #561, #559, #504

[Francisco-Gamino]

LGTM

[VasylZvarydchuk]

That's a great fix @AnatoliB. Thank you very much. We spent tons of time to refactor our PowerShell functions previously worked fine in Azure Automation. It took much time to investigate these weird errors and add Out-Null statements. How to know when this fix will be release?

[AnatoliB]

@VasylZvarydchuk Expect this to be deployed to Azure within ~3-4 weeks.

[VasylZvarydchuk]

@AnatoliB we still see such errors. Apparently, this change doesn't fix the problem. So, if code has such code like return $null PowerShell Azure Functions fails with Cannot bind argument to parameter 'InputObject' because it is null

[AnatoliB]

@VasylZvarydchuk The 3-4 weeks estimate turned out to be overoptimistic. For reasons unrelated to the fix, the rollout to Azure was delayed. It is happening right now, and many regions already have the fix. Please check the Functions runtime version for your app on the Portal (the Overview tab): if you see 3.0.15371 or higher, you've got the fix. Otherwise, you may need to wait for a few more days and/or restart the app.

If you are on 3.0.15371 and still see the problem, please file a new issue, as this is probably something else.

[VasylZvarydchuk]

Thank you @AnatoliB . I see we have still 3.0.15193.0. Ok, waiting.

[VasylZvarydchuk]

@AnatoliB just today we have got a new AF update and indeed the fix works. Thank you very much