[FIX] stock: Owner filter crash

Current behavior:
Filter "Owner is not set" on Package in inventory app was causing a traceback

Steps to reproduce:
- Go in inventory app
- Go in package
- Apply a filter "Owner is not set"
- You get a traceback

opw-2714726

closes odoo/odoo#82229

X-original-commit: e4b35090
Signed-off-by: Nicolas Lempereur (nle) <nle@odoo.com>
Signed-off-by: Engels Robin (roen) <roen@odoo.com>