volunteers/app/controllers/application_controller.rb

class ApplicationController < ActionController::Base
  before_action :configure_permitted_parameters, if: :devise_controller?

  include Pundit::Authorization
  alias :current_user :current_member
  rescue_from Pundit::NotAuthorizedError, with: :user_not_authorized

  protected

  def configure_permitted_parameters
    devise_parameter_sanitizer.permit(:sign_up, keys: [:name , :arriving , :leaving])
  end

  def user_not_authorized
    flash[:alert] = "You are not authorized to perform this action."
    redirect_back(fallback_location: root_path)
  end
end