[FIX] account: prevent traceback while remove currency and company

Expected singleton: res.currency() when currency not provided
also when remove company in invoice.

Steps to Produce:-
- While go to invoice and click on `REGISTER PAYMENT`
- Remove currency from wizard

Traceback will be generated.

Applying this changes will resolve this issue.

sentry - 4149615534

closes odoo/odoo#121625

Signed-off-by: William André (wan) <wan@odoo.com>