Prevent crash in case `base.default_user` has been deleted. Note that the user shouldn't be deleted in a first place, but that's another discussion... opw-2360615 closes odoo/odoo#60821 X-original-commit: 7342cadcfe8d85edb8a53aef0ecc402dbbc7e935 Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>