[FIX] point_of_sale: ensure customer presence for `split_transactions`

This commit addresses an issue where `split_transactions` payments were
allowed to be added without adding a customer during the creation of
return orders. The problem led to errors during session closure.

The solution is that in the backend when creating return orders and
adding payments, enforce the presence of a customer for
`split_transactions` by showing an error.

opw-3468160

closes odoo/odoo#132096

X-original-commit: 6f20626b
Signed-off-by: David Monnom (moda) <moda@odoo.com>
Signed-off-by: Pedram Bi Ria (pebr) <pebr@odoo.com>

addons/point_of_sale/i18n/point_of_sale.pot

@@ -1733,6 +1733,7 @@ msgstr ""
 #. module: point_of_sale
 #. odoo-javascript
 #: code:addons/point_of_sale/static/src/js/Screens/PaymentScreen/PaymentScreen.js:0
+#: code:addons/point_of_sale/wizard/pos_payment.py:0
 #, python-format
 msgid "Customer is required for %s payment method."
 msgstr ""

addons/point_of_sale/wizard/pos_payment.py

@@ -3,6 +3,7 @@
 
 from odoo import api, fields, models, _
 from odoo.tools import float_is_zero
+from odoo.exceptions import UserError
 
 
 class PosMakePayment(models.TransientModel):
@@ -43,6 +44,12 @@ class PosMakePayment(models.TransientModel):
         self.ensure_one()
 
         order = self.env['pos.order'].browse(self.env.context.get('active_id', False))
+        if self.payment_method_id.split_transactions and not order.partner_id:
+            raise UserError(_(
+                "Customer is required for %s payment method.",
+                self.payment_method_id.name
+            ))
+
         currency = order.currency_id
 
         init_data = self.read()[0]