class Slack::Web::Faraday::Response::RaiseError

def on_complete(env)
  if env.status == 429
    fail Slack::Web::Api::Errors::TooManyRequestsError, env.response
  elsif (body = env.body) && body['ok']
    return
  else
    fail Slack::Web::Api::Errors::SlackError.new(body['error'], env.response)
  end
end