Comment 3 for bug 1645842

This is the part in the code where the crash happened: http://bazaar.launchpad.net/~widelands-dev/widelands/casern_workersqueue/view/7437/src/ui_fsmenu/launch_mpg.cc#L302

So this is my guess what happened and I think it is independent of the win condition chosen: Since this was not a default map, it needed to be downloaded from the site. If a player does not have a map downloaded, the host will send it to the player when she joins the game.

Gun did join the game and received the meta information (settings_->settings() in this case), containing win condition and map filename. win_condition_load() assumes that if !settings_->settings().mapfilename.empty() this contains a valid map filename. map.get_correct_loader(settings_->settings().mapfilename) probably returns nullptr (did not check this), because the map is not yet there - the host did not send it yet. And so the code crash.

Most of this menu stays blank until the map has been received and this logic needs to be implemented at this place too.