Changing line item quantities on cancelled orders leads to stock management discrepancies

[filipefurtad0]

Description

When an order is cancelled, the quantity from a given line item is returned to the on_hand amount, for that variant.
After this it is possible to edit the order, and reduce the line item amount or remove the line item, which also returns them to the on_hand amount. Doing so ends up with an on_hand increased amount, up to 2x the initial one.

Expected Behavior

It should not be possible to change the amount of a line item or to remove a line item, in cancelled orders; to do so, the order should be resumed.

Actual Behaviour

It is possible to change the amount of a line item or to remove a line item, in cancelled orders, without resuming the order.

Steps to Reproduce

1. Set a on_hand amount for a variant to = 3
2. Place an order with a line item, quantity: 3
3. Check your stock: Expect it to be out of stock.
4. Cancel the order.
5. Check your stock again: Expect it to = 3. (cancelling an order automatically returns the item)
6. Edit the order.
7. Set the quantity for that item to = 0; or click the trash bin and remove the line item.
8. Check your stock again: It is now = 6.... (twice as much as in the beginning...)

Animated Gif/Screenshot

Steps 6 - 8:

Workaround

Severity

A customer can place orders when the displayed stock does not display the original settings - s2 i think

Your Environment

• Version used: v3.6.8
• Browser name and version: Firefox 86
• Operating System and version (desktop or mobile): Ubuntu 20.04

Possible Fix