main.rb

module A
  module B
    class Manager
      include Module A::B::Notification
      
      at_exit do
        if $ERROR_INFO
          error = {
            timnestamp: Time.now,
            message: $ERROR_INFO.message,
            backtrace: $ERROR_INFO.backtrace,
            gems: Gem.loaded_specs.inject({}) do |m, (n, s)|
              m.merge(n => s.version)
            end
           }
          send_mail YAML.dump(error)
        end
      end
    end
  end
end

module A
  module B
    module Notification
      def send_mail 
        # send mail via pony
      end
    end
  end
end