[BUG] "Restart Extensions" after extension updates causes misleading "backend couldn't be determined" error

[tfenster]

Describe the bug
If you use the recently added "Restart extension" action, you will get a misleading error message

To Reproduce
Steps to reproduce the behavior:

1. Have some extension updates to make the "Restart extensions" button appear in the extensions section
2. Click on that action
3. Error message "backend couldn't be determined" appears

Expected behavior
No error message

Screenshots
None

System Information

• OS: Windows
• Alpaca Version (VS Code Extension): 1.23.0

Additional context
Markus has already started to investigate based on a debugging session with Manfred, I think

[tfenster]

Tracked 4PS-internally at https://dev.azure.com/4psnl/Alpaca/_backlogs/backlog/Alpaca%20Team/Stories?workitem=1008