When you see the message, run this from another terminal:

  $ gdb
  (gdb) attach 1234
  (gdb) set detach-on-fork off
  (gdb) continue

Normally GDB will stop when the child process receives SIGSEGV.  At that
point, you should be able to type “bt” to get the backtrace.

Could you try that?

Thanks in advance,
Ludo’.