[FIX] incorrect way to get partner_id

pos_order_load/models/pos_order.py

@@ -77,8 +77,8 @@ class PosOrder(models.Model):
         return {
             'id': order.id,
             'name': order.pos_reference,
-            'partner_id': self.partner_id.id,
-            'orderlines': orderlines
+            'partner_id': order.partner_id.id,
+            'orderlines': orderlines,
         }
 
     @api.model