Here is the sample code of how you get the default shipping address information of the customer
* @var CustomerRepositoryInterface
Try the below code and let me know if you need more details.
$customerRepository = Magento\Customer\Api\CustomerRepositoryInterface
$addressRepository = Magento\Customer\Api\AddressRepositoryInterface
//define above variables in constructor.
$customer = $this->customerRepository->getById($customerId);
$shippingAddressId = $customer->...
After digging into the JS and template files, then tracing back to the PHP code, I discovered there is a bug in the core Magento Shipping module (vendor/magento/module-shipping).
In this file:
On line 63, we have:
<?php $id = $item->getId() ?? $item->getOrderItemId();...
I realise this is an old post, although this may be helpful to someone reaching this in the future.
The above answers detailed above suggest to Map a JS file, to a copy of the same JS file with modifications. I'd suggest against this, unless absolutely necessary, as when you upgrade the site to higher Magento 2 versions, things can change in the original JS ...