* Fix: Undefined variable `$child_order_item_id` PHP warning in `wc_mnm_get_order_item_container()` on every uncached lookup, introduced by a stale merge in 2.9.0.
* Fix: Fatal error rendering any Print Invoices and Packing Lists document when PIP is older than 3.14.3, introduced by a stale merge in 2.9.0.
* Fix: `wc_mnm_order_item_container_size_meta_value` filter parameters corrected to container level `$args, $container_item_hash`.
* Fix: Remove unused `$context` param from `is_in_stock()` and `is_purchasable()` methods in the `WC_MNM_Child_Item` class.
* Fix: Add missing `_wc_mnm_packing_mode` meta key when creating a new order item for a Mix and Match product in the admin.

Enhancement: Escape and sanitize shortcode output.

* Tweak – WordPress 7.1 Compatibility.

* Misc – Tested up to WooCommerce 11.0.1 and WordPress 7.0.3