benschwarz/amnesia — pull request #5 by jerefrer (2012-04-25 10:08:16+00:00)
Title: Fixed bug with Array sum method.

After installing amnesia, adding it to my config.ru and starting my server again, I got this error :

undefined method `zero?' for nil:NilClass

I googled around and found [this is coming from your definition of the sum method for Array](http://stackoverflow.com/questions/8899272/rails-3-undefined-method-zero-for-nilnilclass-in-many-to-many-relationsh)

So I replaced Array sum method definition with the one in Rails's Enumerable. I don't know if the whole definition is needed but at least my app is now running fine.

I see you're using Ruby 1.9.2 and I'm still on 1.8.7 so this may be an 1.8.7 related issue.
Couldn't manage to run your tests to confirm it though.

Tell me if it's still working fine for you :)