Fix fatal error when canceling uncaptured orders due to non-expanded refunds in Stripe API response

[james-allan]

Fixes #3371

Changes proposed in this Pull Request:

When we bumped the Stripe API version in 8.5.0 to 2024-06-20 we introduced the potential for a fatal error when cancelling uncaptured orders.

In version 2022-11-15, Stripe changed the default response for charges to no longer automatically expand the refunds property.

^{refunds no longer expanded. Source: https://docs.stripe.com/upgrades#2022-11-15}

This caused a fatal error when attempting to cancel an uncaptured charge because we expected the charge object to have refund data. This PR fixes that by making sure we fetch the charge and expand the refunds array before attempting to access it.

Testing instructions

1. Go to WooCommerce > Settings > Payments > Stripe > Settings
2. Enable the "issue an authorization on checkout, and capture later" option
3. Purchase a product using Stripe
4. Attempt to cancel the order.
   • On develop you will receive the following error.
   • On this branch no error should occur.

PHP Fatal error:  Uncaught Error: Attempt to modify property "data" on null in /wp-content/plugins/woocommerce-gateway-stripe/includes/abstracts/abstract-wc-stripe-payment-gateway.php:1130
Stack trace:
#0 /wp-content/plugins/woocommerce-gateway-stripe/includes/class-wc-stripe-order-handler.php(348): WC_Stripe_Payment_Gateway->process_refund(8772)
#1 /wp-includes/class-wp-hook.php(326): WC_Stripe_Order_Handler->cancel_payment(8772)
#2 /wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters(NULL, Array)
#3 /wp-includes/plugin.php(517): WP_Hook->do_action(Array)
#4 /wp-content/plugins/woocommerce/includes/class-wc-order.php(416): do_action('woocommerce_ord...', 8772, Object(Automattic\WooCommerce\Admin\Overrides\Order), Array)
#5 /wp-content/plugins/woocommerce/includes/class-wc-order.php(257): WC_Order->status_transition()
#6 /wp-content/plugins/woocommerce/includes/admin/meta-boxes/class-wc-meta-box-order-data.php(768): WC_Order->save()
#7 /wp-includes/class-wp-hook.php(326): WC_Meta_Box_Order_Data::save(8772)
#8 /wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters(NULL, Array)
#9 /wp-includes/plugin.php(517): WP_Hook->do_action(Array)
#10 /wp-content/plugins/woocommerce/src/Internal/Admin/Orders/Edit.php(313): do_action('woocommerce_pro...', 8772, Object(Automattic\WooCommerce\Admin\Overrides\Order))

---

• Covered with tests (or have a good reason not to test in description ☝️)
• Added changelog entry in both changelog.txt and readme.txt (or does not apply)
• Tested on mobile (or does not apply)

Post merge

• Added testing instructions to the Release Testing Instructions wiki page (or does not apply)
• Added the needs docs label (or does not apply)
• Included this PR in the Release Thread scope (or does not apply)

[Mayisha]

Thanks @james-allan. The changes look good to me 🎉

I can not reproduce the fatal error. But I have confirmed that in the develop branch the $response is null for me in the previous code,
$response = end( $charge->refunds->data );

In this branch, I see the correct data in $response with the updated code

{"id":"re_3PsKL8CBKj0yxC0Z0NDMDq1J","object":"refund","amount":3800,"balance_transaction":null,"charge":"ch_3PsKL8CBKj0yxC0Z0aSOpBIm","created":1724745702,"currency":"eur","destination_details":{"card":{"reference":"676489","reference_status":"available","reference_type":"system_trace_audit_number","type":"reversal"},"type":"card"},"metadata":{},"payment_intent":"pi_3PsKL8CBKj0yxC0Z0sGDowhm","reason":null,"receipt_number":null,"source_transfer_reversal":null,"status":"succeeded","transfer_reversal":null}