The partitions are typically already unmounted when wrimg.sh runs, so
umount prints 'not mounted' to stderr. This is harmless but noisy.
Redirect stderr to /dev/null and use || true so the warning is silenced.
Copyright (C) 2026 Brendan Szymanski <hello@bscubed.dev>
check_device() was using lsblk -o LABEL (filesystem labels) to identify
partitions, but mkimg.sh sets the labels via e2label which can silently
fail if the partition image wasn't built with an ext4 filesystem label.
The system partition in particular often shows as '/' (the mkfs.ext4
default) instead of 'system'.
Switch to lsblk -o PARTLABEL (GPT partition names), which are always set
correctly by mkimg.sh via sfdisk's name= parameter, and are preserved
regardless of filesystem layer.
Also broaden find_device() to check sde and mmcblk[01] entries.
Copyright (C) 2026 Brendan Szymanski <hello@bscubed.dev>
