Error (index out of range) when saving SVG as DXF

This is a near-duplicate of the expired question here:
https://answers.launchpad.net/inkscape/+question/631890

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What I was trying to do: I imported an SVG and tried to save it as a DXF.

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Expected behavior: Save without error

Actual behavior: Dialog box pops up with an error that approximately looks like:

Traceback (most recent call last):
  File "dxf_outlines.py", line 360, in <module>
    e.affect()
  File "/usr/share/inkscape/inkex.py", line 283, in affect
    self.effect()
  File "dxf_outlines.py", line 344, in effect
    h = self.unittouu(self.document.getroot().xpath('@height', namespaces=inkex.NSS)[0])
IndexError: list index out of range

and then a dialog saying that the save failed.

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Tech details: running Inkscape 0.92.2 on Linux Ubuntu 18.04

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Fix: The fix detailed in the linked question worked for me. As suggested by marenhachmann, replacing the offending line with:

h = self.unittouu(self.getDocumentHeight())

produces the expected behavior.