Error when converting PDF generated by pdfLaTeX if there are big vertical lines

[UlyssesZh]

How to reproduce:

echo '\documentclass{article}\\begin{document}$\\big|$\\end{document}' | pdflatex
pdftowrite texput.pdf

The error:

Traceback (most recent call last):
  File "/home/ulysses/.pyenv/versions/3.10.6/bin/pdftowrite", line 8, in <module>
    sys.exit(main())
  File "/home/ulysses/.pyenv/versions/3.10.6/lib/python3.10/site-packages/pdftowrite/pdftowrite.py", line 187, in main
    run(sys.argv[1:])
  File "/home/ulysses/.pyenv/versions/3.10.6/lib/python3.10/site-packages/pdftowrite/pdftowrite.py", line 164, in run
    pages = loop.run_until_complete( convert_to_pages(filename, page_nums, ns) )
  File "/home/ulysses/.pyenv/versions/3.10.6/lib/python3.10/asyncio/base_events.py", line 646, in run_until_complete
    return future.result()
  File "/home/ulysses/.pyenv/versions/3.10.6/lib/python3.10/site-packages/pdftowrite/pdftowrite.py", line 114, in convert_to_pages
    result = await asyncio.gather(*tasks)
  File "/home/ulysses/.pyenv/versions/3.10.6/lib/python3.10/concurrent/futures/thread.py", line 58, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/home/ulysses/.pyenv/versions/3.10.6/lib/python3.10/site-packages/pdftowrite/pdftowrite.py", line 104, in process_page
    return Background(page_num, svg, text_layer_svg, not ns.no_compat_mode)
  File "/home/ulysses/.pyenv/versions/3.10.6/lib/python3.10/site-packages/pdftowrite/docs.py", line 70, in __init__
    self.__process_svg(svg, text_layer_svg, compat_mode, uniquify)
  File "/home/ulysses/.pyenv/versions/3.10.6/lib/python3.10/site-packages/pdftowrite/docs.py", line 92, in __process_svg
    self.text_layer = self.__create_text_layer(text_layer_svg)
  File "/home/ulysses/.pyenv/versions/3.10.6/lib/python3.10/site-packages/pdftowrite/docs.py", line 284, in __create_text_layer
    tree = ET.ElementTree( ET.fromstring(text_layer_svg) )
  File "/home/ulysses/.pyenv/versions/3.10.6/lib/python3.10/xml/etree/ElementTree.py", line 1342, in XML
    parser.feed(text)
xml.etree.ElementTree.ParseError: not well-formed (invalid token): line 24, column 22

Environment:

• OS: Ubuntu 20.04.4 LTS
• Python: 3.10.6
• pdftowrite: 2021.5.3
• Inkscape: 1.2 (1:1.2.1+202207142221+cd75a1ee6d)
• TeX: 3.14159265 (TeX Live 2019/Debian)