This map has always been broken. This variant makes it slightly less broken (although something changed on the ceiling might prevent hiding on pixels on the slope). What will finally fix it is either moving nets closer together or adding angle bounce to hedgehogs or some other layout that prevents hiding.
/*
** $Id: ldebug.h,v 2.3.1.1 2007/12/27 13:02:25 roberto Exp $
** Auxiliary functions from Debug Interface module
** See Copyright Notice in lua.h
*/
#ifndef ldebug_h
#define ldebug_h
#include "lstate.h"
#define pcRel(pc, p) (cast(int, (pc) - (p)->code) - 1)
#define getline(f,pc) (((f)->lineinfo) ? (f)->lineinfo[pc] : 0)
#define resethookcount(L) (L->hookcount = L->basehookcount)
LUAI_FUNC void luaG_typeerror (lua_State *L, const TValue *o,
const char *opname);
LUAI_FUNC void luaG_concaterror (lua_State *L, StkId p1, StkId p2);
LUAI_FUNC void luaG_aritherror (lua_State *L, const TValue *p1,
const TValue *p2);
LUAI_FUNC int luaG_ordererror (lua_State *L, const TValue *p1,
const TValue *p2);
LUAI_FUNC void luaG_runerror (lua_State *L, const char *fmt, ...);
LUAI_FUNC void luaG_errormsg (lua_State *L);
LUAI_FUNC int luaG_checkcode (const Proto *pt);
LUAI_FUNC int luaG_checkopenop (Instruction i);
#endif