Without the null check for shipping address, an exception would be thrown and Magento would crash, but only if the product is virtual. Virtual products doesn't have a shipping address, only a billing address. Adding this null check makes the module compatible with Magento 2.2.6.
Without the null check for shipping address, an exception would be thrown and Magento would crash, but only if the product is virtual. Virtual products doesn't have a shipping address, only a billing address. Adding this null check makes the module compatible with Magento 2.2.6.