bug#64487: 29.0.92; Another tree-sitter warning inside Custom

[Dmitry Gutov <dmitry@gutov.dev>]

On 26/02/2024 19:02, Eli Zaretskii wrote:
>> Date: Mon, 26 Feb 2024 18:55:09 +0200
>> Cc:luangruo@yahoo.com,64487@debbugs.gnu.org
>> From: Dmitry Gutov<dmitry@gutov.dev>
>>
>> I remember you saying that it was a question which is settled until any
>> other problems come up. Isn't this an example of such problem?
> No, I don't think so.  It is a very special case, which is rarely a
> problem (only if the user decides eventually not to activate the
> mode).

Which mode, though?

The sequence of actions does not pertain to any particular mode: it's 
just Customize -> Programming -> Languages.

Going through these steps with 'emacs -Q' here, I got both a warning 
about the missing lua grammar (14 lines tall), and both ruby-ts-mode and 
  elixir-ts-mode added to auto-mode-alist, which weren't there before.

And then visiting the "C" node (which is not specific to the tree-sitter 
modes, to be clear -- it's mostly CC Mode variables), I get also 
c-ts-mode, c++-ts-mode and c-or-c++-ts-mode added there.

There would be more modes added, but apparently some use groups with no 
parent defined (such as 'java' or 'json'), so they're not reachable from 
the general Customize interface.