I want to use LaravelShoppingcart by Crinsane but this error has tangled me " Please supply a valid identifier."

I tried to integrate Crinsane's "Shopping Cart" but I do not know what I'm wrong with.

screenshot with cartcontroller enter image description here

screennshot with cart.php enter image description here

structure folders enter image description here

I apologize for uploading pictures and I did not put the code here.

via Chebli Mohamed