custom_error_handling.rb

# option #1
# Granted, this would require that bugsnag be a dependency of the gem. And, that might
# not be an option. but, anyhoo
module Crex
  # This could be a parent class that is configured in a similar way api_client gem does
  class RescueStrategy
    def self.call(e)
      Bugsnag.notify(e)
    end
  end

  class Experiment
    def allocate
      # do stuff
    rescue => e
      RescueStrategy.call(e)
    end
  end
end

Crex::Experiment.new.allocate

# option #2
module Crex
  class Experiment
    def allocate(rescue_strategy: nil)
      # do stuff
    rescue => e
      if rescue_strategy
        rescue_strategy.notify(e)
      end
    end
  end
end

# Provided by client
class MyCustomRescueStrategy
  def self.notify(e)
    Bugsnag.notify(e)
  end
end