portlint -AC
rclint
poudriere testport
make test (if available) - may uncover hidden errors, not required to pass 100%, but good to take a look at.

Also - if you tested the resulting application - please not that too.

sysutils/dkron/Makefile
1	Please remove. No longer needed after migration to git
19	Please group USES= and USE_*= together
24	Do I understand correctly that you can't use `GO_MODULE=` here because the software is v3 and it doesn't respect go's version subdirectory convention?
181	You don't install anything into `${STAGEDIR}${ETCDIR}` here. I assume it's a bug?
sysutils/dkron/files/dkron.in
3	This is not required anymore, please remove.
54	If the user explicitly asks for syslog logging, but the daemon doesn't support it - the error will just be silenced. IMO it's not good, could you add an error message here?
82	You don't really need to check for this. `install -d` is idempotent
sysutils/dkron/pkg-plist
1	Do you need `%%ETCDIR%%` to be writable by `dkron`, or just readable? If the latter - than it's more secure to let root own `%%ETCDIR%%`
2	Consider dynamically creating `/var/*` directories in `precmd` in the RC script, an not including it in the pkg-plist. This will allow the service to work fine if the /var is backed by memdisk, and populated at boot.
4	If this is the only config file - you don't really need a `%%ETCDIR%%` for it, you may just install it into `%%PREFIX%%/etc/dkron.yml.sample` You have the line `@comment`-ed out, is it a typo?