This fixes an accounting migration issue that could cause errors when assigning outstanding credits to invoices. The update ensures the process uses the correct invoice reference, helping migrations complete more reliably.

during the conversion of the method "assign_outstanding_credit",
the id parameter was wrongly kept. Now that we are working with
recordsets, the id is now stored in self.id

This fixes an error that occurred when users tried to remove a tip through the barcode scanner flow. The change helps warehouse and point-of-operation staff complete barcode actions without being blocked by an unexpected failure.

Issue:https://www.odoo.com/web#id=673097&view_type=form&model=project.issue&action=609&menu_id=4720