nomarchy-build-iso and nomarchy-build-live-iso both ran under set -e
but then wrapped nix build in an if [ \$? -eq 0 ] block with an else
that printed "Error: ISO build failed." and exit 1. set -e aborts the
script the instant nix build returns non-zero, so the else branch was
never reached — the user saw nix build's own error output and the
script exited.
Removed the dead conditional. Behaviour is identical.