Working through the Agile Web Development w/ Rails book on p114. I can
add single items of each to the cart but when I try to add a second item
I get the following error:
NoMethodError in StoreController#add_to_cart
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.+
Any idea why this is happening? Thanks.