- When resending a failed mail the code could crash.
The issue is caused by the fact that calling `_get_recipient_data`
with the parameter `pids` only, returns as the partners' groups the
value `None`.
The codes that uses the result of this method consider the groups as
an iterable and crash when trying to iterate on a `NoneType`.
OPW-1916498
closesodoo/odoo#29408