Eli Zaretskii <eliz@gnu.org> writes:

>> Date: Thu, 26 Dec 2019 13:04:20 +0000
>> From: Alan Third <alan@idiocy.org>
>> Cc: 38748@debbugs.gnu.org
>> 
>> > 20  org.gnu.Emacs                 	0x00000001084a7c86 handle_sigsegv + 168
>> > 21  libsystem_platform.dylib      	0x00007fff6b73a42d _sigtramp + 29
>> > 22  ???                           	000000000000000000 0 + 0
>> > 23  org.gnu.Emacs                 	0x00000001084ddd80 mark_object + 272
>> > 24  org.gnu.Emacs                 	0x00000001084ddd80 mark_object + 272
>> 
>> Looks like a crash in GC.
>
> Yes, but why?
>
> One possibility is stack overflow.  If that's not the reason, then one
> needs to employ the technique described in etc/DEBUG to find out which
> object got corrupted and why.

I followed the steps described in etc/DEBUG.

Emacs is configured using:
'configure --without-xml2 --with-ns --with-modules
 --disable-ns-self-contained --enable-checking=yes,glyphs
 --enable-check-lisp-object-type 'CFLAGS=-O3 -g3''

See gdb session output attached.

Hope this will help.