Facebook認証の実装に失敗し、"Invalid route name, already in use:"と表示されてしまいます

Question

前提・実現したいこと

Facebookのログイン認証機能を実装しようとしています。

https://ticklecode.com/fb_omniauth/

上記のリンクに従って実装を進めていたところ、以下のようなエラーメッセージが発生しました。

発生している問題・エラーメッセージ

.../vendor/bundle/ruby/2.5.0/gems/actionpack-5.1.6/lib/action_dispatch/routing/route_set.rb:588:in `add_route': 
  Invalid route name, already in use: 'destroy_user_session'  (ArgumentError)
You may have defined two routes with the same name using the `:as` option, or you may be overriding a route already defined by a resource with the same naming. For the latter, you can restrict the routes created with `resources` as explained here:
http://guides.rubyonrails.org/routing.html#restricting-the-routes-created

該当のソースコード

/config/routes.rb

Rails.application.routes.draw do

  get 'users/:id', to: 'users#show', as: :user_show
  root :to => 'users#index'

  # コールバック用URL
  devise_for :users, controllers: { omniauth_callbacks: 'users/omniauth_callbacks' }

  # ログアウト用
  devise_scope :user do
    delete :sign_out, to: 'devise/sessions#destroy', as: :destroy_user_session
  end

end

/app/users/omniauth_callbacks_controller.rb

class Users::OmniauthCallbacksController < Devise::OmniauthCallbacksController
  def facebook
    callback_from :facebook
  end

  private

  def callback_from(provider)
    provider = provider.to_s

    @user = User.find_for_oauth(request.env['omniauth.auth'])

    if @user.persisted?
      flash[:notice] = I18n.t('devise.omniauth_callbacks.success', kind: provider.capitalize)
      sign_in_and_redirect @user, event: :authentication
    else
      session["devise.#{provider}_data"] = request.env['omniauth.auth']
      redirect_to new_user_registration_url
    end
  end
end

/app/models/user.rb

class User < ApplicationRecord
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable, :omniauthable

  def self.find_for_oauth(auth)
    user = User.where(uid: auth.uid, provider: auth.provider).first

    unless user
      user = User.create(
        uid:      auth.uid,
        provider: auth.provider,
        email:    User.dummy_email(auth),
        password: Devise.friendly_token[0, 20]
      )
    end

    user
  end

  private

  def self.dummy_email(auth)
    "#{auth.uid}-#{auth.provider}@example.com"
  end
end

補足情報（FW/ツールのバージョンなど）

• rbenv: 1.1.0
• Rails: 5.1.6
• Ruby: ruby 2.5.0p0 (2017-12-25 revision 61468) [x86_64-darwin16]
• 初心者のため、情報に不足がありましたがご指摘頂けますと幸いです..

---

お助け頂けましたら幸いです、よろしくお願い致します..

Answer 1

解決できました！

下記の部分がいらないようです！

# ログアウト用
  devise_scope :user do
    delete :sign_out, to: 'devise/sessions#destroy', as: :destroy_user_session
  end

参考：

https://stackoverflow.com/questions/40243507/logout-routing-using-oauth-and-rails?rq=1