instance_setup.ps1 report write-log error if $script:activate_instance_script_loc return is empty

Write-Log : Cannot bind argument to parameter 'msg' because it is an empty string.
At C:\Program Files\Google\Compute Engine\sysprep\instance_setup.ps1:251 char:15
+ Write-Log "$_"
+ ~~~~
+ CategoryInfo : InvalidData: (:) [Write-Log], ParameterBindingValidationException
+ FullyQualifiedErrorId : ParameterArgumentValidationErrorEmptyStringNotAllowed,Write-Log

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Add where before the foreach solve the issue
& $script:activate_instance_script_loc | where {$_} | ForEach-Object {
Write-Log "$_"