Dynamic crontab dir

On NixOS, I tend to get errors like this:

I get this error because CRON_COMMAND is hardcoded to /usr/bin/crontab #L148

Given that NixOS is non-FHS compliant which binaries are stored in /nix/store are there any refactors for it?

such as this

CRON_COMMAND = os.system('which crontab')

Thanks