Fix unarchiving of mapheader_t userdata Lua variables

src/lua_script.c

@@ -853,7 +853,7 @@ static UINT8 UnArchiveValue(int TABLESINDEX)
 		LUA_PushUserdata(gL, &sectors[READUINT16(save_p)], META_SECTOR);
 		break;
 	case ARCH_MAPHEADER:
-		LUA_PushUserdata(gL, &sectors[READUINT16(save_p)], META_MAPHEADER);
+		LUA_PushUserdata(gL, mapheaderinfo[READUINT16(save_p)], META_MAPHEADER);
 		break;
 	case ARCH_TEND:
 		return 1;