exceptatron.rb

module Exceptatron
  class Middleware
    def initialize app
      @app = app
    end

    def call request
      raise StandardError.new "Bubbling down"

      code, headers, body = @app.call request

      raise StandardError.new "Bubbling up"

      [code, headers, body]
    end
  end
end

Rails.application.middleware.insert_before Rack::Lock, Exceptatron::Middleware
Rails.application.middleware.insert_after Rack::Lock, Exceptatron::Middleware