char buf[max (sizeof "from..to..in " + 2 * INT_STRLEN_BOUND (EMACS_INT),
max (sizeof " . #" + INT_STRLEN_BOUND (intmax_t),
max ((sizeof " with data 0x"
+ (sizeof (uintmax_t) * CHAR_BIT + 4 - 1) / 4),
40)))];
current_thread->stack_top = buf; <<<<<<<<<<<<<<<<<<<<<<<<<<
If you remove the indicated line, does the crash go away?
If removing that line doesn't help, please tell the dimension of the
buf[] array that the code above calculates? In GDB, this is possible
with the command 'ptype'; I don't know what is the lldb equivalent.