Gateways where shopping carts are allowed give warnings for products with no weight

Problem/Motivation

Gateways where shopping carts are allowed (f.e. Klarna) give warnings for products with no weight.

In src/Helpers/OrderHelper.php function getShoppingCartData variable $productWeight is declared (line 547 till 553). This can be NULL. At line 585 and 586 $productWeight is accessed as an array. If $productWeight is NULL then this will result in a warning on PHP 7.4 or higher.

Steps to reproduce

Use a gateway where shopping carts are allowed (f.e. Klarna) and buy a product without a weight.

Proposed resolution

A simple isset check before accessing the $productWeight variable will fix the warning.

Remaining tasks

User interface changes

API changes

Data model changes