[FIX] purchase: prevent traceback when creating PO without company_id

when the user removes the company_id and add a line in the purchase order
then the issue is generated.

Steps to reproduce:

- Create a new purchase order.
- Remove the company_id in the Purchase order.
- Now add a line in PO. Select a product with the consumable product type.
- Traceback will be generated.

Applying these changes will resolve this issue.

Sentry-4215579151

closes odoo/odoo#123061

Signed-off-by: Tiffany Chang <tic@odoo.com>