NoMethodError in Admin/base#error_404

Showing themes/asnap/views/shared/_menu.html.erb where line #8 raised:

undefined method `any?' for nil:NilClass
Extracted source (around line #8):

5:   cache_key << RefinerySetting.find_or_set(:refinery_menu_cache_action_suffix, "site_menu")
6:   cache_key << request.path
7:   cache(cache_key.join('_')) do
8:     if (collection ||= @menu_pages).any?
9: -%>
10:       <nav id='<%= dom_id %>' class='<%= %W(#{css} clearfix).join(' ') %>'>
11:         <%= render :partial => "/shared/menu_branch",
Trace of template inclusion: themes/asnap/views/pages/show.html.erb