'Compare with Saved' crashes the PowerShell session

[ajansveld]

System Details

• Operating system name and version: Windows 10 (10.0.14393)
• VS Code version: 1.15.0 (8b95971d8cccd3afd86b35d4a0e098c189294ff2)
• PowerShell extension version: 1.4.1
• Output from $PSVersionTable:

Name                           Value
----                           -----
PSVersion                      5.1.14393.1532
PSEdition                      Desktop
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
BuildVersion                   10.0.14393.1532
CLRVersion                     4.0.30319.42000
WSManStackVersion              3.0
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1

Issue Description

When using the "Compare with Saved" feature on a PowerShell script the extension stops with a "The PowerShell session has terminated due to an error, would you like to restart it?" message.

I think the bug is actually in the language server, but raising it here for visibility (sorry for the cross-post).

Attached Logs

See PowerShell/PowerShellEditorServices#544.

[daviwil]

No problem! I actually just started looking into this one again, expect a fix in the next update.

[daviwil]

I've got a fix prepared for this, will go out with today's update! Closing it as a duplicate of PowerShell/PowerShellEditorServices#342.