strange crash when exporting pbcore

[NumerousHats]

Traceback (most recent call last):
File "/home/andrec/.local/pipx/venvs/autoBWF/lib/python3.8/site-packages/autoBWF/autoBWF.py", line 704, in export_metadata
write_pbcore(vals["outfile"], md, self.filename, ohms_file, vals["audacity_button"])
File "/home/andrec/.local/pipx/venvs/autoBWF/lib/python3.8/site-packages/autoBWF/bwf2pbcore.py", line 156, in write_pbcore
pbcore = generate_pbcore(bwf_filename, metadata, ohms_root)
File "/home/andrec/.local/pipx/venvs/autoBWF/lib/python3.8/site-packages/autoBWF/bwf2pbcore.py", line 99, in generate_pbcore
add_multivalue_child(pbcore_root, "pbcoreSubject", metadata["names"], {"subjectType": "name"})
File "/home/andrec/.local/pipx/venvs/autoBWF/lib/python3.8/site-packages/autoBWF/bwf2pbcore.py", line 58, in add_multivalue_child
child.set(attribute, attributes[attribute])
AttributeError: 'NoneType' object has no attribute 'set'

Might be a bit hard to reproduce...