class Devise::OmniauthCallbacksController

def failure_message
  exception = request.respond_to?(:get_header) ? request.get_header("omniauth.error") : request.env["omniauth.error"]
  error   = exception.error_reason if exception.respond_to?(:error_reason)
  error ||= exception.error        if exception.respond_to?(:error)
  error ||= (request.respond_to?(:get_header) ? request.get_header("omniauth.error.type") : request.env["omniauth.error.type"]).to_s
  error.to_s.humanize if error
end