HTML Zip download build broken on readthedocs

[DocOtak]

Read the docs uses a custom builder called "readthedocssinglehtmllocalmedia" when building the downloadable html zipfile. This failed with the message "Furo is being used as an extension in a non-HTML build. This should not happen." It looks like this is due to a change introduced here: 3631ffc#diff-dc7d5958a7254d9617ea5b9f26d584dead466926f6a3e72768eaf0384865e0b1R230-R232 that limited furo to specific named builders.

[gboeing]

Same issue here using RTD and the latest Sphinx 7.2.2. May be related to #693 and #708? Output:

Running Sphinx v7.2.2
making output directory... done

Traceback (most recent call last):
  File "/home/docs/checkouts/readthedocs.org/user_builds/osmnx/envs/latest/lib/python3.11/site-packages/sphinx/cmd/build.py", line 293, in build_main
    app = Sphinx(args.sourcedir, args.confdir, args.outputdir,
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/docs/checkouts/readthedocs.org/user_builds/osmnx/envs/latest/lib/python3.11/site-packages/sphinx/application.py", line 272, in __init__
    self._init_builder()
  File "/home/docs/checkouts/readthedocs.org/user_builds/osmnx/envs/latest/lib/python3.11/site-packages/sphinx/application.py", line 343, in _init_builder
    self.events.emit('builder-inited')
  File "/home/docs/checkouts/readthedocs.org/user_builds/osmnx/envs/latest/lib/python3.11/site-packages/sphinx/events.py", line 96, in emit
    results.append(listener.handler(self.app, *args))
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/docs/checkouts/readthedocs.org/user_builds/osmnx/envs/latest/lib/python3.11/site-packages/furo/__init__.py", line 234, in _builder_inited
    raise ConfigError(
sphinx.errors.ConfigError: Furo is being used as an extension in a non-HTML build. This should not happen.

Configuration error:
Furo is being used as an extension in a non-HTML build. This should not happen.

[dgw]

I'd bet #710 will resolve it.

[dylanljones]

Also running into this issue with readthedocs (Sphinx 7.2.3, Furo 2023.8.19) after fixing the problem discussed in #693.

sphinx.errors.ConfigError

Traceback (most recent call last):
  File "/home/docs/checkouts/readthedocs.org/user_builds/pyrekordbox/envs/latest/lib/python3.11/site-packages/sphinx/cmd/build.py", line 293, in build_main
    app = Sphinx(args.sourcedir, args.confdir, args.outputdir,
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/docs/checkouts/readthedocs.org/user_builds/pyrekordbox/envs/latest/lib/python3.11/site-packages/sphinx/application.py", line 272, in __init__
    self._init_builder()
  File "/home/docs/checkouts/readthedocs.org/user_builds/pyrekordbox/envs/latest/lib/python3.11/site-packages/sphinx/application.py", line 343, in _init_builder
    self.events.emit('builder-inited')
  File "/home/docs/checkouts/readthedocs.org/user_builds/pyrekordbox/envs/latest/lib/python3.11/site-packages/sphinx/events.py", line 96, in emit
    results.append(listener.handler(self.app, *args))
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/docs/checkouts/readthedocs.org/user_builds/pyrekordbox/envs/latest/lib/python3.11/site-packages/furo/__init__.py", line 234, in _builder_inited
    raise ConfigError(
sphinx.errors.ConfigError: Furo is being used as an extension in a non-HTML build. This should not happen.

[pradyunsg]

Resolved in 5abeb9f -- I'll cut a release for this sometime this weekend. :)