def handle_error(e, name, args, job)
      if error_handler = Backburner.configuration.on_error
        if error_handler.arity == 1
          error_handler.call(e)
        elsif error_handler.arity == 3
          error_handler.call(e, name, args)
        else
          error_handler.call(e, name, args, job)
        end
      end
    end
Handles an error according to custom definition
Used when processing a job that errors out