Adding an item to the cart fails when you have never called getCart

[sthomas69]

To reproduce the bug follow these steps:-

1. A new user (an account that is not known by Auth0) logs in they get a token from Auth0.
2. Find an item and call .../cart/add/1 for example. The number of the item is not important
3. You receive a 404 error when using the ...azurewebsites.net or you get a 500 error when running the enterprise-musicstore-api-aspnet locally using Visual Studio

Basically, the cart for the new user is not getting created before placing the item into it!

The workaround was to call getCart and then the call to .../cart/add/1 succeeds.

The bug can only be recreated using an account that has never called getCart.

[fenix2222]

#16