Given modular app, with some external logger

class ApplicationController < Sinatra::Base
  enable :logging

  set(:logger) { SomeAwesomeModule.logger }
  configure do
    use ::Rack::CommonLogger, settings.logger
  end

  errors do
    logger.error env['sinatra.error'].message
  end
end

and this will raise output all error in dev & prod environments twice- first time with the logger and the second time from dump_errors extension.

class ApplicationController < Sinatra::Base
  disable :dump_errors

helps to fix it. Maybe it is a feature, which i just did not get. Anyway, i feel like at least issue should be created and/or readme updated. or maybe disable :dump_errors with custom logger.

Anyway, hope this the situation a bit more clear and maybe save someone's else day.