If you register online on a free event, there is an
access rights error when trying to download the ICS file
if you are connectd with public user.
`if not event` part is pointless, if event cannot be resolved,
@http.route would return a 404 anyway.
`if not event.registration_ids` does not make sense from a
functional point of view: there is no problem in generating
an .ics file for a public event that has no registrations (yet)
and the button we use to generate the .ics file is displayed
after the registration anyway.
opw-2066847
closesodoo/odoo#37012
X-origin-commit: f4ca5897df9295b684bcbfcafd98fbde2f8bf673
Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>
Ics file generation should be possible even when only event is
installed as it is a basic feature of events.
Moreover we need to be able to generate such files in order to replace
the old outlook api used in the event templates, api which is not
supported anymore.
We decided to use ics files because it is supported by most calendar
schedulers hence working with outlook.
Linked to task #1853063closesodoo/odoo#28477