Saving Optimized SVG error

[Francesco]

In certain cases when saving an optimized SVG the plugin will crash without saving the file.
Flag checked:
- Shorten color values
- Convert CSS attributes
- Group collapsing
- Create groups for similar attributes
- Embed rasters
- Work around render bugs
- Enable viewboxing
- number of significant digits for coords: 5
- XML indentation: space

Error reported:
Traceback (most recent call last):
  File "scour.inkscape.py", line 78, in <module>
    e.affect(output=False)
  File "C:\Program Files\Inkscape\share\extensions\inkex.py", line 265, in affect
    self.getposinlayer()
  File "C:\Program Files\Inkscape\share\extensions\inkex.py", line 207, in getposinlayer
    x = self.unittouu( xattr[0] + 'px' )
  File "C:\Program Files\Inkscape\share\extensions\inkex.py", line 351, in unittouu
    return retval * (self.__uuconv[u.string[u.start():u.end()]] / self.__uuconv[self.getDocumentUnit()])
  File "C:\Program Files\Inkscape\share\extensions\inkex.py", line 304, in getDocumentUnit
    p = param.match(svgwidth)
TypeError: expected string or buffer

[Alvin Penner (apenner)]

thank you for taking the time to issue a report!

not reproduced on Windows 10, Inkscape 0.92pre3 15195

appears to be a duplicate of Bug 1463623