fix

app/models/system_notification.rb

@@ -17,8 +17,4 @@ class SystemNotification < ApplicationRecord
 
   scope :is_top, lambda { where(is_top: true) }
 
-
-  def read_member?(user_id)
-    self.system_notification_histories.where(user_id: user_id).present? ? true : false
-  end
 end