Fix crash when untitled files are opened as PowerShell

[rjmholt]

Fixes PowerShell/vscode-powershell#1649.

Finding dot-sourced references when we parse script files currently relies on the file having a directory, which is not true for untitled files.

This is a simple fix for the crash that occurs as a result.

If there's interest, I could try and improve the situation by changing the visitor to have a null PSScriptRoot mean ignore PSScriptRoot paths, or even try to make an untitled dir... (1st feels like it has merit, second maybe not).

[SeeminglyScience]

LGTM!

If there's interest, I could try and improve the situation by changing the visitor to have a null PSScriptRoot mean ignore PSScriptRoot paths, or even try to make an untitled dir... (1st feels like it has merit, second maybe not).

How about making it the working directory? That should accomplish the same as the untitled drive, and would be most likely what someone is going for using $PSScriptRoot in an untitled file.

[TylerLeonhardt]

I can't like @SeeminglyScience's comment... but if I could I 100% would

[rkeithhill]

BTW this scenario via F8 does not work in ISE.

C:\Users\Keith
12-15 16:40:25 56ms 2> . $PSScriptRoot\test.ps1
. : The term '\test.ps1' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or 
if a path was included, verify that the path is correct and try again.

OTOH ISE doesn't crash. I dunno, I think the right answer might be what @rjmholt has implemented for the untitled scenario - just punt on analyzing dot sourced files using $PSScriptRoot. Seems like the more we try to support this scenario, the more we are setting folks up for failure later (no breakpoint support, etc). I view this scenario for folks just wanting to play around a little bit.

[rkeithhill]

LGTM

[rkeithhill]

I wouldn't bother but that is just my 2 cents.

[rjmholt]

I'm going to favour simplicity here. We can work out if we really want to support untitled files later I think.