Dear Maintainer,

When I accidentally start an unconfigured instance of openvpn-server@
(or, probably, openvpn-client@), it fails to start, but keeps trying
to start it every 5s.

This could happen from a typo, or from attempting to start the wrong
end of the tunnel, or similar scenarios.

A method that seems to work is to add to the unit file:

[Unit]
AssertPathExists=/etc/openvpn/server/%i.conf

I don't know whether %i or %I is better there.

Thanks,
Richard