[FIX] lunch: allow location_id to be NULL
[FIX] lunch: allow location_id to be NULL

In case the last location of a user was NULL in databse, lunch was
crashing because lunch_kanban was adding an undefined leaf to the load
domain.

closes odoo/odoo#36571

Signed-off-by: Yannick Tivisse (yti) <200a91eb0e5cc4726d6a3430713b580138f34298@odoo.com>

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