[FIX] sale_payment: catch error at invoice creation

- Set up Paypal as described in
  https://www.odoo.com/documentation/user/11.0/ecommerce/shopper_experience/paypal.html
- Buy a product on the eCommerce.

The vendor might receive an email mentioning that Instant Payment
Notifications (IPN) are failing.

When completing the paypent process with Paypal, 2 confirmations of the
transaction will occur. The first one is through the route
`/payment/paypal/dpn` (Payment Data Transfer (PDT)), which takes place
right after the payment validation. The second confirmation comes
through the route `/payment/paypal/ipn` (Instant Payment Notification
(IPN)), which might arise with some delay (and potentially being run
several times).

Both confirmations will trigger the method `_generate_and_pay_invoice`,
which can raise an error if no invoiceable line is found ('There is no
invoiceable line.' in `sale` module). In this case, we should log the
error and move forward instead of crashing and stopping the workflow.

More information on PDT and IPN at
https://developer.paypal.com/docs/classic/ipn/integration-guide/IPNPDTAnAlternativetoIPN/

opw-1837196

addons/sale_payment/models/payment.py

@@ -3,6 +3,7 @@
 import logging
 
 from odoo import api, fields, models, _
+from odoo.exceptions import UserError
 from odoo.tools import float_compare
 
 _logger = logging.getLogger(__name__)
@@ -84,8 +85,16 @@ class PaymentTransaction(models.Model):
         # force_company needed for company_dependent fields
         ctx_company = {'company_id': self.sale_order_id.company_id.id,
                        'force_company': self.sale_order_id.company_id.id}
-        created_invoice = self.sale_order_id.with_context(**ctx_company).action_invoice_create()
-        created_invoice = self.env['account.invoice'].browse(created_invoice).with_context(**ctx_company)
+
+        # We might fail to create the invoice because there is no invoiceable lines. This will
+        # raise a UserError and break the workflow. Better catch the error.
+        try:
+            created_invoice = self.sale_order_id.with_context(**ctx_company).action_invoice_create()
+            created_invoice = self.env['account.invoice'].browse(created_invoice).with_context(**ctx_company)
+        except UserError:
+            _logger.warning('<%s> transaction completed, could not auto-generate invoice for %s (ID %s)',
+                            self.acquirer_id.provider, self.sale_order_id.name, self.sale_order_id.id, exc_info=True)
+            return
 
         if created_invoice:
             _logger.info('<%s> transaction completed, auto-generated invoice %s (ID %s) for %s (ID %s)',