Incomplete requirements / failure to fail on missing cpio

[fl42v]

The kexec tarball of nixos requires cpio installed, and it's not always present.

One example would be to try to deploy on a machine booted from live archiso [addit: also need to mount /dev/sda1 /root]. The script in question would complain about missing cpio but continue anyway, which results in a black screen and nothing else happening. With pacman -Sy cpio ran before deploying, everything works as it's supposed to.

Also, it seems a bit weird the installation did continue at all after that error, since both scripts have set -e