Durante varios días, las compilaciones de ReadTheDocs fallan y no sé por qué.

Los errores no tienen sentido para mí. No me dicen cuál de los documentos es malo ni por qué.

Las cosas que han cambiado en las últimas semanas han sido que estoy usando mi editor de rebajas de una manera que se integra directamente en GitHub. Y he estado agregando iframes de recetas de repl.it en el libro de cocina. No creo que el archivo Léame aún tenga ninguno.

No creo que sean los iframes porque están en funcionamiento en el libro de cocina actual que se encuentra aquí.
http://cookbook.PySimpleGUI.org

Léame está aquí:
http://www.PySimpleGUI.org

¡Cualquier ayuda será muy apreciada!

Aquí hay una compilación de ejemplo:
https://readthedocs.org/projects/pysimplegui/builds/8589243/

Build #8589243
latest (1eb3c26878e321867fb1dc28d94353d2087fed3f)
Build failed
git clone --no-single-branch --depth 50 https://github.com/PySimpleGUI/PySimpleGUI .
git checkout --force origin/master
git clean -d -f -f
python3.7 -mvirtualenv --no-site-packages --no-download /home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/envs/latest
/home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/envs/latest/bin/python -m pip install --upgrade --cache-dir /home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/.cache/pip pip
/home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/envs/latest/bin/python -m pip install --upgrade --cache-dir /home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/.cache/pip Pygments==2.2.0 setuptools<40 docutils==0.13.1 mock==1.0.1 pillow==2.6.1 alabaster>=0.7,<0.8,!=0.7.5 commonmark==0.5.4 recommonmark==0.4.0 mkdocs==0.17.3
cat mkdocs.yml
python /home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/envs/latest/bin/mkdocs build --clean --site-dir _build/html --config-file /home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/checkouts/latest/mkdocs.yml
INFO    -  Cleaning site directory 
INFO    -  Building documentation to directory: /home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/checkouts/latest/_build/html 
Traceback (most recent call last):
  File "/home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/envs/latest/lib/python3.7/site-packages/mkdocs/nav.py", line 337, in _follow
    raise StopIteration
StopIteration

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/envs/latest/bin/mkdocs", line 10, in <module>
    sys.exit(cli())
  File "/home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/envs/latest/lib/python3.7/site-packages/click/core.py", line 764, in __call__
    return self.main(*args, **kwargs)
  File "/home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/envs/latest/lib/python3.7/site-packages/click/core.py", line 717, in main
    rv = self.invoke(ctx)
  File "/home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/envs/latest/lib/python3.7/site-packages/click/core.py", line 1137, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/envs/latest/lib/python3.7/site-packages/click/core.py", line 956, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/envs/latest/lib/python3.7/site-packages/click/core.py", line 555, in invoke
    return callback(*args, **kwargs)
  File "/home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/envs/latest/lib/python3.7/site-packages/mkdocs/__main__.py", line 156, in build_command
    ), dirty=not clean)
  File "/home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/envs/latest/lib/python3.7/site-packages/mkdocs/commands/build.py", line 282, in build
    build_pages(config, dirty=dirty)
  File "/home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/envs/latest/lib/python3.7/site-packages/mkdocs/commands/build.py", line 213, in build_pages
    site_navigation = nav.SiteNavigation(config)
  File "/home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/envs/latest/lib/python3.7/site-packages/mkdocs/nav.py", line 44, in __init__
    config, self.url_context)
  File "/home/docs/checkouts/readthedocs.org/user_builds/pysimplegui/envs/latest/lib/python3.7/site-packages/mkdocs/nav.py", line 392, in _generate_site_navigation
    config_line, url_context, config):
RuntimeError: generator raised StopIteration