[FIX] stock: Lot/Serial Number not displayed
[FIX] stock: Lot/Serial Number not displayed

The field lot_name is not initialised in many cases.

Steps to reproduce the bug:

- Set your user in the group called "Display Serial & Lot Number in Delivery Slips"
- Create a new stockable product P with setting tracking "by unique serial number"
- Create 10 serial numbers for P
- Purchase 10 units of P and select the 10 serial numbers created
- Create a SO where I selected 1 unit of P with its serial number and confirm it
- Go to the delivery slip and print the delivery slip

Bug:

The serial number was not printed in the delivery slip.

opw:1900735

closes odoo/odoo#28076
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo