destroy wiki menu item when corresponding page is destroyed

app/models/wiki_page.rb

@@ -47,12 +47,18 @@ class WikiPage < ActiveRecord::Base
   # Wiki pages that are protected by default
   DEFAULT_PROTECTED_PAGES = %w(sidebar)
 
+  after_destroy :delete_wiki_menu_item
+
   def after_initialize
     if new_record? && DEFAULT_PROTECTED_PAGES.include?(title.to_s.downcase)
       self.protected = true
     end
   end
 
+  def delete_wiki_menu_item
+    self.menu_item.destroy if self.menu_item
+  end
+
   def visible?(user=User.current)
     !user.nil? && user.allowed_to?(:view_wiki_pages, project)
   end