Fine-tuning of a8dbbc029d1e86c84, similar to d76cd50f0e
Avoid error of 'user_type_readonly' referenced before assignment.
This can happen during database migration or if the module category is deleted.
closesodoo/odoo#38190
X-original-commit: cf1e5198e32e9239a6d3cbbfdc325dbd3e0952de
Signed-off-by: Nans Lefebvre (len) <len@odoo.com>