We have a lot of game data errors, some of them localized, some of them not. Example:
throw game_data_error(_("building %1$u: %2$s"), serial, e.what()); throw game_data_error(_("flagdata: %s"), e.what());
Do we want to localize these or not? I guess this is info for the devs in case a bug comes up, so should these stay in English?