Finding 1: no-arg branch used 'ls ... | while' which, under set -euo
pipefail, exits 1 on an empty backups dir (glob matches nothing). Replace
with shopt nullglob array check that prints a clear message and exit 0.
Finding 2: pass $TS and $SNAP_NAME as positional args to the inner alpine
shell instead of interpolating them into the sh -c string, making the swap
injection-proof. Behavior unchanged: pre-restore copy -> clear WAL/SHM -> install.