Both REST /add-smartphone-to-cart/ and /add-to-cart/ not working

[Pengu1no]

What happened?

I've created Angular 7 frontend application. Each endpoint worked well except cart adding. Sending POST request does not adds products to cart. When I tried to add serializer.save() into core shop.views.catalog I got errors and I have no idea how to proceed
P.S. User is authenticated

What should've happened instead?

Product should appear in the cart

Steps to reproduce

• Add new product to database
• Authenticate (ex. JWT)
• Send POST to add to cart

OR

• Add new product to database
• Authenticate (in-box authentication)
• Open /slug/add-smartphone-to-cart/
• Send any value in post

Profit!

OS: Ubuntu 18.04, local run

[Pengu1no]

P.P.S. Library code is not needed to be changed to reproduce issue

[jrief]

Could you please tell me which values you are sending to the endpoint .../add-to-cart/.
Did you compare these values with those sent by the browser, if the project has been set up through cookiecutter?

[Pengu1no]

Yep, I've followed readme

[Pengu1no]

My screenshots



And since my "qwerty" product is smartphone I cannot use /add-to-cart/ (screenshot below)