Fix segfault when ghost dies from a death pit

src/p_mobj.c

@@ -3139,6 +3139,7 @@ boolean P_SceneryZMovement(mobj_t *mo)
 
 	if (P_CheckDeathPitCollide(mo))
 	{
+		if (mo->type != MT_GHOST)  // ghosts play death animations instead, so don't remove them
 			P_RemoveMobj(mo);
 		return false;
 	}