fix load engine error

lib/announcement/engine.rb

@@ -105,6 +105,10 @@ module Announcement
             puts ['there_was_no_show_option_method',e]
           end
           if File.basename($0) != 'rake'
+            gem_root = Announcement::Engine.root
+            require File.join(gem_root, 'app/models/bulletin_feed')
+            require File.join(gem_root, 'app/models/bulletin_feed_cache')
+            require File.join(gem_root, 'app/models/anns_cache')
             begin
               avoid_page_cache AnnsCache
               avoid_page_cache BulletinFeedCache

lib/announcement/migrate.rb

@@ -7,10 +7,9 @@ module Announcement
       require File.join(gem_root, 'app/models/bulletin')
       require File.join(gem_root, 'app/models/bulletin_feed')
       require File.join(gem_root, 'app/models/bulletin_feed_cache')
+      require File.join(gem_root, 'app/models/anns_cache')
 
-      require File.join(Announcement::Engine.root, 'app/models/anns_cache')
-
-      setting = AnnouncementSetting.first
+      setting = AnnouncementSetting.first || AnnouncementSetting.create
 
       if !setting.migrate_flag.include?("v1")
         Bulletin.all.pluck(:id, :title).each do |id, title_translations|