Steps:

1. Create a new Product.
2. Create base price using REST API -> base price is created, user can see it on UI

POST http://127.0.0.1:8000/api/ibexa/v2/product/catalog/products/example/prices
X-CSRF-Token: {{CSRF_TOKEN}}
Content-Type: application/vnd.ibexa.api.PriceCreateStruct+json
Accept: application/json

{
  "PriceCreateStruct": {
    "amount": 2500,
    "currency": "EUR"
  }
} 

1. Send the same request with changed amount.

Result: Second base price with new id is created, no changes in UI.

Expected result: Product should not have more than one base price for a given currency