Get a line number where Write-Error occurred - powershell

Question

Consider the script
$someComplexCondition = $false
if ($someComplexCondition)
{
Write-Error -Message "Some complex condition"
}
else
{
Write-Error -Message "Other complex condition"
}
When I run it it says
C:\Dev> .\MyScript.ps1
C:\Dev\MyScript.ps1 : Other complex condition
At line:1 char:15
+ .\MyScript.ps1 <<<<
+ CategoryInfo : NotSpecified: (:) [Write-Error], WriteErrorException
+ FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,MyScript.ps1
And I noticed that Write-Error always reports itself as at line:1
According to the stack trace it looks like it's line #1 because it was called from the shell and more interesting char:15 because
".\MyScript.ps1 ".Length -eq 15
If we change file name, this char:15 will be changed accordingly.
The question is how to get the actual line when the error occurred.
In our case I would like to get line:9

Answer 1

When there is an actual error, generated by Powershell you get an object of the type ErrorRecord :
$error[0] | Get-Member
TypeName: System.Management.Automation.ErrorRecord
When you use this same ErrorRecord with Write-Error, you don't get an object :
$myError = Write-Error -ErrorRecord $Error[0]
PS C:\> $MyError | Get-Member
gm : You must specify an object for the Get-Member cmdlet.
At line:1 char:12
+ $MyError | gm
+ ~~
+ CategoryInfo : CloseError: (:) [Get-Member], InvalidOperationException
+ FullyQualifiedErrorId : NoObjectInGetMember,Microsoft.PowerShell.Commands.GetMemberCommand
So now, we know that Write-Error will not give us anything that we can reuse later.
You can use the "Throw" statement, instead :
$someComplexCondition = $false
if ($someComplexCondition)
{
Throw "Some complex condition"
}
else
{
Throw "Other complex condition"
}
Then, when you run the script, the error gives you the line number and character number of the start of the "Throw" statement :
C:\Test-Error.ps1
Other complex condition
At C:\Test-Error.ps1:9 char:5
+ Throw "Other complex condition"
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : OperationStopped: (Other complex condition:String) [], RuntimeException
+ FullyQualifiedErrorId : Other complex condition
Here, it is line number 9.