Why is my store cart not updating quantity?

[DecorTeam]

Very much experimental stage currently I have noticed my store CART is not operating.

Is this something I have done wrong or is this scripting error in the theme?

There are a handful of products on the catalog, but when I add any of these to the cart the pop up appears yet the quantity in the cart does not change.

https://decorandstuff.myshopify.com