Problems "must be of type string (or int), null given" and Memcached

[DimitriBouriez]

Prerequisites

• I understand and accept the project's code of conduct.
• I have already searched in existing issues and found no previous report of this bug.

Describe the bug and add attachments

I had a problem with retrieving the stock location for products that are no longer available when viewing an old order. Normally, this should return false when the stock location is not found. But when the Memcached cache is active, the null value is returned, causing a fatal error. This must be linked to the fact that Memcached doesn't distinguish between null and false.

To correct my specific problem, I added the following processing at the end of the setProductCurrentStock() method in /classes/order/Order.php:
if ($product['location'] === null) {
$product['location'] = false;
}

This ensures that false is returned and not null.

The following issues seem to be affected by a similar bug:
#22215
#35753
#35979

Expected behavior

No response

Steps to reproduce

1. Enable Memcached cache
2. Create an order
3. Delete an ordered product from the catalog
4. View order

PrestaShop version(s) where the bug happened

8.1.2

PHP version(s) where the bug happened

No response

If your bug is related to a module, specify its name and its version

No response

Your company or customer's name goes here (if applicable).

No response

[florine2623]

Hello @DimitriBouriez ,

Do you have the same issue with memcached disabled ?

Thanks!

[DimitriBouriez]

Hello @florine2623 ,
Once the Memcached cache is deactivated, everything works as expected.
Regards,

[florine2623]

@PrestaShop/qa-functional
Can someone try to reproduce this issue please ? I'm encountering this error while testing.