fix: correctly display interaction with nil description in HTML view

Author: bethesque

lib/pact/doc/sort_interactions.rb

@@ -8,7 +8,7 @@ def self.call interactions
       private
 
       def self.sortable_id interaction
-        "#{interaction.description.downcase} #{interaction.response.status} #{(interaction.provider_state || '').downcase}"
+        "#{(interaction.description || '').downcase} #{interaction.response.status} #{(interaction.provider_state || '').downcase}"
       end
     end
   end