Josh,
We have fixed this issue and pushed the changes to Github repository. Could you please pull the latest code and try out your application on it?
We had defined one method called log using rb_define_singleton_method() and it was conflicting with the built-in method with the same name (log) called by Math.log invoked by number_to_human_size. We have renamed our method to log_message to prevent this collision.
Thanks for reporting this issue and offering to look in to it!
Aditya