I'm not either. Is it Dosbox crashing or RubyBox? Can you start RubyBox from terminal with 'rbox' and paste the error? I've seen one Ruby crash error with the new packages. Ruby code shouldn't crash the interpreter, but I bet I can avoid triggering that bug. But this seems unrelated to that.
~ $ rbox ./settings.rb:218:in `list_mappers': undefined method `[]' for nil:NilClass from rbox.rb:19:in `each_with_index' from ./settings.rb:213:in `each' from ./settings.rb:213:in `each_with_index' from ./settings.rb:213:in `list_mappers' from ./settings.rb:377:in `load_game' from rbox.rb:64:in `load_game' from ./launcher.rb:302:in `game_settings' from ./launcher.rb:62:in `initialize' from rbox.rb:269:in `call' from rbox.rb:269:in `main' from rbox.rb:269 ~ $