bug#48337: Fwd: 28.0.50; Emacs crashing randomly (possibly minibuffer activity related)

[Eli Zaretskii <eliz@gnu.org>]

> From: Alex Bennée <alex.bennee@linaro.org>
> Date: Mon, 10 May 2021 20:30:58 +0100
> Cc: Alan Mackenzie <acm@muc.de>
> 
> It seems my mail client left this in the sent folder but never actually sent it:
> 
>   I haven't been able to find a reproduction as the bug hits fairly
>   randomly hence I'm running in my normal init.el heavy environment.
>   That said there shouldn't be anything in lisp that could cause a
>   segfault in the core C code.
> 
>   This only started happening this week after a recent update from
>   master (I update every Monday). The only change I could see that might
>   be related was f608b4b93 (Prevent the selected window being a dead
>   mini-window when switching frames).
> 
>   Unfortunately no symbols. However both core dumps so far have seen the
>   same null XCAR being called from nth_minibuffer:
> 
>   #0  0x00007f4384f585cb in raise (sig=sig@entry=11) at ../sysdeps/unix/sysv/linux/raise.c:50
>           set = {__val = {18446744067266837247, 0 <repeats 15 times>}}
>           pid = <optimized out>
>           tid = <optimized out>
>   #1  0x000055b6738bf530 in terminate_due_to_signal (sig=sig@entry=11,
> backtrace_limit=backtrace_limit@entry=40) at emacs.c:437
>   #2  0x000055b6738bf97d in handle_fatal_signal (sig=sig@entry=11) at sysdep.c:1762
>   #3  0x000055b6739b8ca8 in deliver_thread_signal (sig=sig@entry=11, handler=0x55b6738bf972
> <handle_fatal_signal>) at sysdep.c:1754
>   #4  0x000055b6739b8d29 in deliver_fatal_thread_signal (sig=11) at sysdep.c:1867
>           fatal = <optimized out>
>   #5  0x000055b6739b8d29 in handle_sigsegv (sig=11, siginfo=<optimized out>, arg=<optimized out>) at
> sysdep.c:1867
>           fatal = <optimized out>
>   #6  0x00007f4384f58730 in <signal handler called> () at /lib/x86_64-linux-gnu/libpthread.so.0
>   #7  0x000055b6739ce0ef in XCAR (c=0x0) at lisp.h:1420
>           tail = 0x0
>           frames = <optimized out>
>           frame = <optimized out>
>           f = <optimized out>
>           innermost_MB = <optimized out>
>   #8  0x000055b6739ce0ef in nth_minibuffer (depth=<optimized out>) at minibuf.c:972
>           tail = 0x0
>           frames = <optimized out>
>           frame = <optimized out>
>           f = <optimized out>
>           innermost_MB = <optimized out>

Please show the Lisp value of Vminibuffer_list.