mkdocs build failing

[planetf1]

As reported via https://lfaifoundation.slack.com/archives/C02M2222F63/p1672667645179079

mkdocs build is failing

ERROR    -  Error building page 'release-notes/1-0.md': can only join an iterable
Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.11.1/x64/bin/mkdocs", line 8, in <module>
    sys.exit(cli())
             ^^^^^
  File "/opt/hostedtoolcache/Python/3.11.1/x64/lib/python3.11/site-packages/click/core.py", line 1130, in __call__
    return self.main(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.11.1/x64/lib/python3.11/site-packages/click/core.py", line 1055, in main
    rv = self.invoke(ctx)
         ^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.11.1/x64/lib/python3.11/site-packages/click/core.py", line 1657, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.11.1/x64/lib/python3.11/site-packages/click/core.py", line 1404, in invoke
    return ctx.invoke(self.callback, **ctx.params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.11.1/x64/lib/python3.11/site-packages/click/core.py", line 760, in invoke
    return __callback(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.11.1/x64/lib/python3.11/site-packages/mkdocs/__main__.py", line 250, in build_command
    build.build(cfg, dirty=not clean)
  File "/opt/hostedtoolcache/Python/3.11.1/x64/lib/python3.11/site-packages/mkdocs/commands/build.py", line 329, in build
    _build_page(file.page, config, doc_files, nav, env, dirty)
  File "/opt/hostedtoolcache/Python/3.11.1/x64/lib/python3.11/site-packages/mkdocs/commands/build.py", line 226, in _build_page
    context = config.plugins.run_event(
              ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.11.1/x64/lib/python3.11/site-packages/mkdocs/plugins.py", line 520, in run_event
    result = method(item, **kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.11.1/x64/lib/python3.11/site-packages/material/plugins/search/plugin.py", line 90, in on_page_context
    self.search_index.add_entry_from_context(page)
  File "/opt/hostedtoolcache/Python/3.11.1/x64/lib/python3.11/site-packages/material/plugins/search/plugin.py", line 149, in add_entry_from_context
    self.create_entry_for_section(section, page.toc, page.url, page)
  File "/opt/hostedtoolcache/Python/3.11.1/x64/lib/python3.11/site-packages/material/plugins/search/plugin.py", line 167, in create_entry_for_section
    title = "".join(section.title).strip()
            ^^^^^^^^^^^^^^^^^^^^^^
TypeError: can only join an iterable
Error: Process completed with exit code 1.

[planetf1]

This has affected only builds since yesterday, and can be replicated locally using mkdocs 1.4.2

The last mkdocs release (on their github repo) was to 1.4.2 on 1 Nov https://github.com/mkdocs/mkdocs
the latest image for our github runner (ubuntu-latest) was 12 Dec - https://github.com/actions/runner-images/blob/main/images/linux/Ubuntu2204-Readme.md -
python 3.11 was 24 Oct https://www.python.org/downloads/

[planetf1]

The error occurs from the mkdocs-material search plugin

        title = "".join(section.title).strip()

[planetf1]

The cause appears to be related to files containing numerics, ie
docs/release-notes/1-0.md
where these are also in the mkdocs.yml navigation index.

Probably some kind of type conversion issue.

[planetf1]

See squidfunk/mkdocs-material#4817

[mandy-chessell]

Thank you @planetf1 for your analysis 👍

I have been thinking that we should consolidate the list in the nav into a consolidated file for the older releases. This is a trigger to do so. I will do that today so we have our builds working again

[planetf1]

The builds are working now. I submitted a pr. another one to follow to reinstate v9 with a workaround from the devs.

Of course that's aside from any changes we want to make

[planetf1]

As per workaround in the mkdocs-material bug report, versions are now quoted, so all should be working at the latest level regardless of any decisions we wish to make to improve our docs.