Redmine › Like Button

When accessing .../projects/.../wiki/index gives:

ActionView::TemplateError (undefined method `title' for nil:NilClass) on line #5 of vendor/plugins/like/app/views/like/wiki/_sidebar.rhtml:
2: <% if settings[:location] == 'sidebar' %>
3:   <% url = request.params[:action] == 'show' ?
4:            canonical_url_for(:controller => 'wiki', :action => 'show', :project_id => project, :id => page.title) :
5:            canonical_url_for(:controller => 'wiki', :action => 'index', :id => project, :page => page.title) %>
6:   <p><%= render(:partial => 'like/common/facebook', :locals => { :url => url }) %></p>
7: <% end %>

The Like button is placed on sidebar...