Error when including apidoc generated files

[nunupeke]

Describe the problem

If I include sphinx apidoc generated files which contain :toctree: directives themselves, I get

File "site-packages\sphinx_jupyterbook_latex\transforms.py", line 300, in apply
KeyError: 'hidden'

when I run

jb build

I wonder why that line is ever called since I don't build anything latex related.

Link to your repository or website

No response

Steps to reproduce

1. add sphinx apidoc generated rst-files like

   API Reference
   =============
   
   .. rubric:: Modules
   
   .. autosummary::
       :toctree: _generate
   
       module1
       module2
   

   to the docs folder.

2. run jb build

The version of Python you're using

No response

Your operating system

No response

Versions of your packages

Jupyter Book : 0.11.2
External ToC : 0.2.2
MyST-Parser : 0.13.7
MyST-NB : 0.12.3
Sphinx Book Theme : 0.1.1
Jupyter-Cache : 0.4.3
NbClient : 0.5.4

Additional context

My current workaround is to change

sphinx-jupyterbook-latex/sphinx_jupyterbook_latex/transforms.py

Line 300 in 43e48a3

if tocnode.attributes["hidden"]:

into

if "hidden" in tocnode.attributes and tocnode.attributes["hidden"]:
    continue

The error first occurred when updating to jupyter-book v0.11, which uses sphinx-external-toc. Therefore executablebooks/sphinx-external-toc#36 may be related.

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[tlambert03]

I'm also having this issue (preventing docs from building on CI at the moment)

jupyter-book 0.11.3
Sphinx 3.5.4
docutils 0.16

Please also report this if it was a user error, so that a better error message can be provided next time.
A bug report can be filed in the tracker at <https://github.com/sphinx-doc/sphinx/issues>. Thanks!
Traceback (most recent call last):
  File "/Users/talley/miniconda3/envs/docs/lib/python3.9/site-packages/jupyter_book/sphinx.py", line 167, in build_sphinx
    app.build(force_all, filenames)
  File "/Users/talley/miniconda3/envs/docs/lib/python3.9/site-packages/sphinx/application.py", line 352, in build
    self.builder.build_update()
  File "/Users/talley/miniconda3/envs/docs/lib/python3.9/site-packages/sphinx/builders/__init__.py", line 296, in build_update
    self.build(to_build,
  File "/Users/talley/miniconda3/envs/docs/lib/python3.9/site-packages/sphinx/builders/__init__.py", line 310, in build
    updated_docnames = set(self.read())
  File "/Users/talley/miniconda3/envs/docs/lib/python3.9/site-packages/sphinx/builders/__init__.py", line 417, in read
    self._read_serial(docnames)
  File "/Users/talley/miniconda3/envs/docs/lib/python3.9/site-packages/sphinx/builders/__init__.py", line 438, in _read_serial
    self.read_doc(docname)
  File "/Users/talley/miniconda3/envs/docs/lib/python3.9/site-packages/sphinx/builders/__init__.py", line 478, in read_doc
    doctree = read_doc(self.app, self.env, self.env.doc2path(docname))
  File "/Users/talley/miniconda3/envs/docs/lib/python3.9/site-packages/sphinx/io.py", line 221, in read_doc
    pub.publish()
  File "/Users/talley/miniconda3/envs/docs/lib/python3.9/site-packages/docutils/core.py", line 219, in publish
    self.apply_transforms()
  File "/Users/talley/miniconda3/envs/docs/lib/python3.9/site-packages/docutils/core.py", line 200, in apply_transforms
    self.document.transformer.apply_transforms()
  File "/Users/talley/miniconda3/envs/docs/lib/python3.9/site-packages/sphinx/transforms/__init__.py", line 86, in apply_transforms
    super().apply_transforms()
  File "/Users/talley/miniconda3/envs/docs/lib/python3.9/site-packages/docutils/transforms/__init__.py", line 171, in apply_transforms
    transform.apply(**kwargs)
  File "/Users/talley/miniconda3/envs/docs/lib/python3.9/site-packages/sphinx_jupyterbook_latex/transforms.py", line 300, in apply
    if tocnode.attributes["hidden"]:
KeyError: 'hidden'