Systemd Unit is broken (official PKGBUILD)

[isopix]

binary works when started directly, but after starting by systemctl start sunrise, it happens (fresh Archlinux with systemd):

Started Sunrise and sunset calculation service.
sunrise.service: Main process exited, code=exited, status=1/FAILURE
sunrise.service: Failed with result 'exit-code'.
sunrise.service: Service RestartSec=100ms expired, scheduling restart.
sunrise.service: Scheduled restart job, restart counter is at 5.
Stopped Sunrise and sunset calculation service.
sunrise.service: Start request repeated too quickly.
sunrise.service: Failed with result 'exit-code'.
Failed to start Sunrise and sunset calculation service

[JimSmith76]

I encounter the same issue on Arch Linux.