[FIX] pos_loyalty: prevent access error in multi-company gift card use

Before this commit, if a gift card was created in another company and
the gift card program was not assigned to any company, using the gift
card in another company resulted in an error.

opw-4422730

closes odoo#194905

X-original-commit: 9eec150
Signed-off-by: Joseph Caburnay (jcb) <jcb@odoo.com>
Signed-off-by: Pedram Bi Ria (pebr) <pebr@odoo.com>

Author: pedrambiria

addons/pos_loyalty/models/loyalty_card.py

@@ -28,7 +28,7 @@ def _get_default_template(self):
         return super()._get_default_template()
 
     def _get_mail_partner(self):
-        return super()._get_mail_partner() or self.source_pos_order_id.partner_id
+        return super()._get_mail_partner() or self.sudo().source_pos_order_id.partner_id
 
     def _get_signature(self):
         return self.source_pos_order_id.user_id.signature or super()._get_signature()