render_detail can sometimes return nil (when no applicable formatter was registered). therefore push html_safe call down.

app/helpers/journals_helper.rb

@@ -48,8 +48,8 @@ module JournalsHelper
     if journal.details.any?
       details = content_tag "ul", :class => "details journal-attributes" do
         journal.details.collect do |detail|
-          if d = journal.render_detail(detail, :cache => options[:cache]).html_safe
-            content_tag("li", d)
+          if d = journal.render_detail(detail, :cache => options[:cache])
+            content_tag("li", d.html_safe)
           end
         end.compact.join(' ').html_safe
       end