Intercept routing errors when consider_all_requests_local = true, only show debugging info is user is logger in

application.rb

[...]
    if Rails.env == "staging"
      require "#{Rails.root}/lib/staging_exception_handler.rb"
      config.middleware.use StagingExceptionHandler
    end
[...]

staging_exception_handler.rb

class StagingExceptionHandler

  def initialize(app)
    @app = app
  end

  def call(env)
    user_id = env["rack.session"]["user_credentials_id"]
    code, _, _ = response = @app.call(env)
    if user_id.blank? && (400..599).include?(code.to_i)
      return ['401', {'Content-Type' => 'text/html'}, ["(#{code}) Danny's not here, Mrs. Torrance."]]
    end

    return response
  end
end