bug#47244: 28.0.50; SIGSEGV in long-runnning Emacs

[Eli Zaretskii]

> From: Michael Welsh Duggan <mwd@cert.org>
> Cc: Michael Welsh Duggan <mwd@md5i.com>,
>         "47244@debbugs.gnu.org"
>  <47244@debbugs.gnu.org>
> Date: Thu, 18 Mar 2021 12:54:20 -0400
> 
> (gdb) p current_buffer->name_
> $8 = XIL(0)
> (gdb) xstring
> $9 = (struct Lisp_String *) 0x0
> "DEAD"

So a buffer that was killed somehow became the current buffer, or the
selected buffer in some window.  I have no idea how that could happen.
At this point, all I can suggest is to try making redisplay simply
return when faced with such buffers, which is really just a band-aid.

Can you tell more about this "resetting" of Gnus, and what it means to
"switch VPN on/off"?