Wagn error on Passenger with Ruby1.9.1

When running Wagn on Debian Lenny, with Ruby 1.9.1p378,  Apache2, mod_rails (Passenger 2.2.11)

It appears when something isn't cached yet by for instance running it in Ruby 1.8, the error appears.

All is fine when running under Ruby 1.8.7 + Passenger 2.2.9.

Also, when running the same production site from console with either Webrick or Mongrel, everything is alright too.

The follow error occurs when viewing pages:

Processing CardController#show (for 82.176.231.90 at 2010-03-18 15:54:23) [GET]

  Parameters: {"id"=>"Home"}

WAGN: per request setup

Rendering template within layouts/application

ActionView::TemplateError (can't convert nil into String) on line #5 of app/views/views/_open.rhtml:

2:      <%= slot.header %>

3: <% end %>

4:

5: <%= slot.wrap_content( slot.render(:expanded_view_content) ) %>

6:

7: <%= slot.notice %>

8: <% if card.ok?(:comment) %> <%#and !card.hard_template %>

    app/models/card/basic.rb:29:in `block in table_of_contents'