Save as > Optimized SVG not working

Steps to reproduce:

• open Inkscape
• draw something
• File > Save as ...
• Select 'Optimized SVG'
• Click OK

What happened?

Traceback (most recent call last):
  File "output_scour.py", line 28, in <module>
    raise inkex.DependencyError("""Failed to import module 'scour'.
AttributeError: 'module' object has no attribute 'DependencyError'

What should have happened?

No error. File should be saved as optimized SVG.

Could it be that the extensions submodule needs to be updated to work with the latest changes in master?

Inkscape Version and Operating System:

• Inkscape Version: 1.1-dev (0ef5c1ec, 2020-02-07) - AppImage, master branch (0ef5c1ec)
• Operating System: Linux Mint 19.3