fix: Patch to make Devise compatible with Rails 8

heartcombo/devise#5728

Author: mishina2228

config/initializers/devise_rails8_patch.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+# Delete this patch when https://github.com/heartcombo/devise/pull/5728 is released.
+
+require 'devise'
+raise 'Devise is not yet available' unless defined? Devise # make sure it's already loaded
+
+module Devise
+  def self.mappings
+    # Starting from Rails 8.0, routes are lazy-loaded by default in test and development environments.
+    # However, Devise's mappings are built during the routes loading phase.
+    # To ensure it works correctly, we need to load the routes first before accessing @@mappings.
+    Rails.application.try(:reload_routes_unless_loaded)
+    @@mappings
+  end
+end