Compare-Object on $null array

 if($Value1 -eq $NULL){
     return
 }
 Compare-Object -ReferenceObject $Value1 -DifferenceObject $Value2

This accepts null values:

Compare-Object -ReferenceObject @($Value1 | Select-Object) -DifferenceObject @($Value2 | Select-Object)

Help on Compare-object says:

If the reference set or the difference set is null ($null), Compare-Object generates a terminating error.

So your only options would seem to be a trap or try/catch.

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