[FIX] base: Fix traceback on draft invoice preview
[FIX] base: Fix traceback on draft invoice preview

Purpose
=======

- fix a traceback when preview a draft invoice while using SEPA QR code.

Specification
=============

- add a condition to not get the length of the communication if the field is not defined.

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo