Processing StoreController#add_to_cart (for 127.0.0.1 at 2009-11-15 06:39:44) [POST]
  Session ID: 6f1c3086794c4e2a819f963d81d3a3a3
  Parameters: {"authenticity_token"=>"d536988ead7480fdcd980ae2eafcc444bab066ec", "id"=>"4"}
  Product Columns (0.9ms)   SHOW FIELDS FROM `products`
  Product Load (0.4ms)   SELECT * FROM `products` WHERE (`products`.`id` = 4)


NoMethodError (You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.<<):
    /app/models/cart.rb:10:in `add_product'
    /app/controllers/store_controller.rb:9:in `add_to_cart'