[Bug]: Restoring a deleted Quotation fails with a server error and leaves it in the trash

Description:

In Sales, quotations that have been deleted can be found under the Archived tab and brought back using the Restore action. Instead of restoring the quotation, the action fails with a server error, and the quotation stays deleted.

Steps to Reproduce:

1. Go to Sales → Orders → Quotations.
2. Delete a quotation.
3. Switch to the Archived tab.
4. Click Restore on the deleted quotation and confirm the action.

Actual Behaviour:

The page shows an Internal Server Error (ErrorException: "Attempt to read property 'warehouse_id' on null"). The restore does not actually happen — the quotation remains in the Archived tab, and its deleted state in the database is unchanged.

Expected Behaviour:

Clicking Restore and confirming should bring the quotation back without any error, and it should immediately show up again in the regular (non-archived) quotations list.

Issue Recording:

https://github.com/user-attachments/assets/31146eef-9d0e-49a3-8c9e-66d8e5b18fa3