Comment 2 for bug 1561443

Thanks for taking the time to file a report!

The bug can be reproduced on Xubuntu 15.10, Inkscape 0.91 and trunk rev.14741.
With the trunk version, the traceback lines are a bit different:
----
Traceback (most recent call last):
  File "ink2canvas.py", line 91, in <module>
    ink.affect()
  File "/usr/local/share/inkscape/extensions/inkex.py", line 284, in affect
    self.effect()
  File "ink2canvas.py", line 86, in effect
    self.walk_tree(svg_root)
  File "ink2canvas.py", line 77, in walk_tree
    self.walk_tree(node)
  File "ink2canvas.py", line 76, in walk_tree
    elem.draw()
  File "/usr/local/share/inkscape/extensions/ink2canvas/svg.py", line 369, in draw
    text = self.text_helper(tspan)
  File "/usr/local/share/inkscape/extensions/ink2canvas/svg.py", line 344, in text_helper
    return ts.text + self.text_helper(ts) + ts.tail
TypeError: coercing to Unicode: need string or buffer, NoneType found