Update PossibleIncorrectComparisonWithNull.md

[KirkMunro]

This is technically more accurate. PowerShell doesn't check for a $null in the array as was previously indicated.

[kapilmb]

Can you please provide a reference for the statement create a new array containing one $null item for each $null in the original array rather than check if the array is null?

[bergmeister]

I think Get-Help about_Comparison_Operators explains this much better:

"When the input to an operator is a scalar value, comparison operators return a Boolean value. When the input is a collection of values, the comparison operators return any matching values. If there are no matches in a collection, comparison operators do not return anything."

Effectively by putting $null on the left hand side, you enforce PowerShell to use the scalar equality comparer, which guarantees a boolean return value (because if $null was on the right hand side, it can return nothing, which can lead e.g. to cases where e.g. if($obj -eq $null) always goes through the if path). I think it would be better to give examples where stuff can go wrong like e.g.:
if( (@() -eq $null) -and (@() -ne $null) ){"This is logically impossible but correct in PowerShell"}

[dlwyatt]

If there are no matches in a collection, comparison operators do not return anything.

Even that's not completely accurate. The comparison operator will return an empty array:

$result = (1..5) -eq $null

$result.GetType().FullName
# System.Object[]

$result.Count
# 0

It's a weird gotcha topic, for sure!

[KirkMunro]

I had completely forgotten about this PR. @dlwyatt's comment drew my attention to it again because I received a notification. I reviewed all comments and updated the text to a slightly corrected version of what is found elsewhere in the help documentation (slightly corrected for the inaccuracy that was identified in that documentation).

[kapilmb]

Thanks @KirkMunro