Signode can not be omitted even object is unreferenable

[SilverRainZ]

#24 breaks LaTeX builder:

make latexpdf of sphinxnotes/lilypond:

Exception occurred:
  File "/usr/lib/python3.11/site-packages/sphinx/writers/latex.py", line 785, in visit_desc_content
    assert self.in_desc_signature
AssertionError
The full traceback has been saved in /tmp/sphinx-err-86ef1j7y.log, if you want to report the issue to the developers.
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!
make: *** [Makefile:23: latexpdf] Error 1

[SilverRainZ]

Use ==2.3.1 to prevent this.