**Steps to produce:**
- Install `website_sale` with demo data.
- Go to the shop page.
- Select product `Customizable Desk` > click `Add to cart`.
- In the wizard, change the quantity to 100 and directly click `Checkout`.

**Issue:**
- The cart shows the product with quantity = 1 instead of the edited value.

Root cause:
- When the user clicks Checkout, both `setQuantity` and `onConfirm` are triggered
  almost simultaneously.
- At [1], the `_setQuantity` method is called, but due to the await before the
  quantity update is completed, the update may not finish in time. As a result,
  the previous quantity is sometimes used during checkout instead of the
  newly selected one.

Solution:
- we can update the quantity immediately before awaiting `_updateCombination`,
  ensuring that the correct quantity is already set when onConfirm runs.

[1]: https://github.com/odoo/odoo/blob/f4eabe47a602301013afa63da6bdf87809903d29/addons/sale/static/src/js/product_configurator_dialog/product_configurator_dialog.js#L225

opw-5435672
---
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Forward-Port-Of: odoo/odoo#241424

Steps to reproduce:
===================
1- Go to Website > eCommerce > Products
2- Open any product and click "Edit website"
3- Add a lot of content blocks (contact form etc..) & save
4- In the product description, delete all content blocks and keep
the last one
5- Click Save

->"Document is empty" validation error appears

Cause:
======
When saving an HTML field after deleting all content, whitespace text
nodes (like newlines) may remain in the DOM element. The
_copy_custom_snippet_translations lang_value might have this
whitespace as the content, which will cause "Document is empty" error
when the content is parsed by fromstring().

This didn't occur before the migration because the previous
implementation called _onSnippetRemoved after a content block was
deleted, and that handler removed any empty elements.
https://github.com/odoo/odoo/blob/8d66c79ecf74900af1c5b003723363be3d52cbc8/addons/website/static/src/components/wysiwyg_adapter/wysiwyg_adapter.js#L1370

Solution:
=========
After removing the content block, we should also do a cleanup.

opw-5263743