Steps to reproduce
------------------
* install `account_peppol`
* open a partner's list view
* select a contact
* on the top middle, click Actions > Verify Peppol
You should be met with a traceback:
`AttributeError: 'bool' object has no attribute 'setdefault'`
Cause
-----
`button_account_peppol_check_partner_endpoint` is expected to return an
action or a falsy value (no action to perform).
opw-3683612
closesodoo/odoo#152817
Signed-off-by: William André (wan) <wan@odoo.com>