SerialisationError when constructing tract network on macOS

[sdmccabe]

Traceback (most recent call last):
  File "construct_tract_network.py", line 128, in <module>
    main(args)
  File "construct_tract_network.py", line 95, in main
    nx.write_graphml(G, f"data/derived/{args.output}/tract_commuter_flows.graphml")
  File "</Users/larock/miniconda3/envs/commuter_nets/lib/python3.8/site-packages/decorator.py:decorator-gen-658>", line 2, in write_graphml_lxml
  File "/Users/larock/miniconda3/envs/commuter_nets/lib/python3.8/site-packages/networkx/utils/decorators.py", line 240, in _open_file
    result = func_to_be_decorated(*new_args, **kwargs)
  File "/Users/larock/miniconda3/envs/commuter_nets/lib/python3.8/site-packages/networkx/readwrite/graphml.py", line 150, in write_graphml_lxml
    writer.dump()
  File "/Users/larock/miniconda3/envs/commuter_nets/lib/python3.8/site-packages/networkx/readwrite/graphml.py", line 696, in dump
    self._xml_base.__exit__(None, None, None)
  File "src/lxml/serializer.pxi", line 1347, in lxml.etree.xmlfile.__exit__
  File "src/lxml/serializer.pxi", line 1685, in lxml.etree._IncrementalFileWriter._close
  File "src/lxml/serializer.pxi", line 1691, in lxml.etree._IncrementalFileWriter._handle_error
  File "src/lxml/serializer.pxi", line 199, in lxml.etree._raiseSerialisationError
lxml.etree.SerialisationError: unknown error -1628709398

It seemed to produce valid output, despite the error.