policyd-spf: IndexError: list index out of range

After updating from spf-engine version 2.9.3 to 3.0.3 (on FreeBSD) I'm getting the following errors from policyd-spf on my syslog:

Apr 6 09:33:17 mail policyd-spf[3692]: Traceback (most recent call last):
Apr 6 09:33:17 mail policyd-spf[3692]: File "/usr/local/bin/policyd-spf", line 8, in <module> sys.exit(main())
Apr 6 09:33:17 mail policyd-spf[3692]: File "/usr/local/lib/python3.9/site-packages/spf_engine/policyd_spf.py", line 97, in main data['recipient'] = data.get('recipient').split('@')[1]
Apr 6 09:33:17 mail policyd-spf[3692]: IndexError: list index out of range

Downgrading to version 2.9.3 makes the problem go away again...

I've tracked the problem down to local network email messages containing recipients without a '@' - recipients like 'sysadmin' 'netadmin'

The originating systems are internal/local systems - and their ip/netmask is already added both to skip_adresses and Whitelists to keep them out of SPF checks - but these checks are never reached before policyd-spf errors out...

The problem is introduced in commit:

commit fa82ae0e8c57183dd020dc7b458a2eeae460a06c
Author: Scott Kitterman <email address hidden>
AuthorDate: Sun Nov 27 19:35:58 2022 -0500
Commit: Scott Kitterman <email address hidden>
CommitDate: Sun Nov 27 19:36:29 2022 -0500

   Changed recipient tracking to only use recipient host name (per RFC 7208) in the policy server if per user processing is not being used and as a result, changedHide_Receiver defau....

Besides being a plain error - this could be misused as a denial-of-service vector by making lots of requests with recipients without '@' in their email addresses

Details: FreeBSD 13.1 with postfix 3.7.4