bug#48479: 28.0.50; Crash on `read--expression'

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: Eli Zaretskii <eliz@gnu.org>,  Mattias Engdegård
>  <mattiase@acm.org>,
>   Richard Stallman <rms@gnu.org>,  48479@debbugs.gnu.org
> Date: Wed, 19 May 2021 16:53:38 +0200
> 
> I agree with Stefan that we should issue a warning...  probably.
> (Depending on whether there's a lot of code out there on this form or
> not.)

I'm also okay with a warning during byte-compilation.