As suggested by vncnt on a different forum, two minor changes are needed to make it work. It works on Inkscape 1.4.2 as well after these manual changes:
For Inkscape 1.3, I think there are only 2 small changes required
diff -r old/svgpath/parser.py new/svgpath/parser.py
595c595
< if link is None or link[0] is not '#':
if link is None or link[0] != '#':
diff --color -r old/svgpath/path.py new/svgpath/path.py
3c3
< from collections import MutableSequence
from collections.abc import MutableSequence
As suggested by vncnt on a different forum, two minor changes are needed to make it work. It works on Inkscape 1.4.2 as well after these manual changes:
For Inkscape 1.3, I think there are only 2 small changes required
diff -r old/svgpath/parser.py new/svgpath/parser.py
595c595
< if link is None or link[0] is not '#':
diff --color -r old/svgpath/path.py new/svgpath/path.py
3c3
< from collections import MutableSequence