bug#72733: 29.4; Warning message while attempting to view customization buffer

[Stefan Kangas <stefankangas@gmail.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: tpeplt <tpeplt@gmail.com>
>> Date: Tue, 20 Aug 2024 10:19:05 -0400
>>
>> Emacs Maintainers,
>>
>>    Emacs 29.4 appears to be running some (uninitialized?) code when a
>> sequence of sub-menus is selected.  This results in a warning message
>> about something that an Emacs user has not selected.  Here is a recipe
>> for reproducing the problem.  I have run this several times and gotten
>> the same result each time.
>>
>> 1. $ emacs -Q
>>
>> 2. M-x customize RET
>>
>> 3. The *Customize Group: Emacs* buffer is displayed.  In this buffer,
>>    select "Programming" from the menu of the Emacs group.
>>
>> 4. The *Customize Group: Programming* buffer is displayed.  In this
>>    buffer, select "Languages" from the menu.
>>
>> 5. A *Warnings* buffer is displayed in a new window.  The following
>>    warning message is displayed in that buffer:
>>
>> ⛔ Warning (treesit): Cannot activate tree-sitter, because language grammar for ruby is unavailable (not-found): (libtree-sitter-ruby libtree-sitter-ruby.0 libtree-sitter-ruby.0.0 libtree-sitter-ruby.so libtree-sitter-ruby.so.0 libtree-sitter-ruby.so.0.0) No such file or directory
>
> It's a known issue for which there's no simple solution.  We want
> users who load ruby-ts-mode to know that they lack the Ruby grammar
> library, which is what this warning is about.  And Customize loads
> ruby-ts-mode to allow its customization when you select Languages.
>
> We could perhaps shut up these specific warnings in that specific
> situation, but that doesn't seem clean.  And the warning is just a
> warning, and harmless.

Showing the warning doesn't seem very clean either.