(gdb) bt
#0  0x00007fcd259cd86b in raise () from /usr/lib/libc.so.6
#1  0x00007fcd259b840e in abort () from /usr/lib/libc.so.6
#2  0x000055fdff156579 in checkpointing (sig=<optimized out>) at comm.c:3526
#3  <signal handler called>
#4  0x000055fdff1bbe14 in queue_enq (q=0x55fe08c8d510, data=0x55fe0df6d750, key=3098) at dg_event.c:180
#5  0x000055fdff1bbef3 in event_create (func=func@entry=0x55fdff1b5fa0 <check_unload_room>, event_obj=event_obj@entry=0x55fe0df6d730, when=<optimized out>) at dg_event.c:49
#6  0x000055fdff1b69cc in schedule_check_unload (room=0x55fe0df6d650, offset=<optimized out>) at db.world.c:3282
#7  0x000055fdff1b6b0b in load_map_room (vnum=477821) at db.world.c:2915
#8  0x000055fdff1886b4 in real_room (vnum=<optimized out>) at db.lib.c:7875
#9  0x000055fdff2ebec0 in real_shift (origin=origin@entry=0x55fe0df3d140, x_shift=x_shift@entry=4, y_shift=y_shift@entry=-1) at utils.c:5058
#10 0x000055fdff2ec07f in find_flagged_sect_within_distance_from_room (room=room@entry=0x55fe0df3d140, with_flags=with_flags@entry=64, without_flags=without_flags@entry=0, distance=4) at utils.c:4754
#11 0x000055fdff1b4511 in get_potential_crop_for_location (location=location@entry=0x55fe0df3d140) at db.world.c:3005
#12 0x000055fdff2844c2 in mapedit_naturalize (ch=0x55fe0b460760, type=<optimized out>, argument=<optimized out>) at olc.map.c:590
#13 0x000055fdff26e0b0 in do_olc (ch=ch@entry=0x55fe0b460760, argument=argument@entry=0x7ffce35577b1 "map nat world", cmd=cmd@entry=20, subcmd=subcmd@entry=0) at olc.c:1091
#14 0x000055fdff233026 in command_interpreter (ch=0x55fe0b460760, argument=<optimized out>) at interpreter.c:1243
#15 0x000055fdff162c91 in game_loop (mother_desc=3) at comm.c:3785
#16 0x000055fdff163ad0 in init_game (port=<optimized out>) at comm.c:3896
#17 0x000055fdff03d695 in main (argc=<optimized out>, argv=<optimized out>) at comm.c:4018