Harden scripts and bump debian-13 ISO to 13.4

debian-13/scripts/package.sh

@@ -1,34 +1,36 @@
 #!/usr/bin/env bash
-set -xu
+set -x
+
+err() {
+	printf "[ERROR]: %s\n" "$1" >&2
+	exit 1
+}
 
 IMG_DIR="./builds/qemu/debian-13-64-vagrant"
-if [ ! -f "$IMG_DIR/debian-13-64-vagrant" ]; then
-	echo "[ERROR]: debian-13-64-vagrant doesn't exist"
-	exit 1
+if [[ ! -f "$IMG_DIR/debian-13-64-vagrant" ]]; then
+	err "debian-13-64-vagrant doesn't exist"
 fi
 
-cat > "$IMG_DIR/metadata.json" <<EOF
+cat >"$IMG_DIR/metadata.json" <<'EOF' || err "failed to write metadata.json"
 {"provider":"libvirt","format":"qcow2","virtual_size":100}
 EOF
 
-cat > "$IMG_DIR/Vagrantfile" <<'EOF'
+cat >"$IMG_DIR/Vagrantfile" <<'EOF' || err "failed to write Vagrantfile"
 Vagrant.configure("2") do |config|
-  config.vm.synced_folder ".", "/vagrant", type: "nfs", nfs_version: 4
+	config.vm.synced_folder ".", "/vagrant", type: "nfs", nfs_version: 4
 end
 EOF
 
-mkdir -p ./builds/vagrant
-
-if [ ! -f ./builds/vagrant/box.img ]; then
-	cp -l $IMG_DIR/debian-13-64-vagrant \
-		$IMG_DIR/box.img
+mkdir -p ./builds/vagrant || err "failed to mkdir ./builds/vagrant"
+if [[ ! -f "$IMG_DIR/box.img" ]]; then
+	cp -l "$IMG_DIR/debian-13-64-vagrant" "$IMG_DIR/box.img" ||
+		err "failed to hardlink 'debian-13-64-vagrant' to 'box.img' file"
 fi
 
-if [ ! -f ./builds/vagrant/debian-13-64-vagrant.box ]; then
+if [[ ! -f ./builds/vagrant/debian-13-64-vagrant.box ]]; then
 	tar -C "$IMG_DIR" -cvzf ./builds/vagrant/debian-13-64-vagrant.box \
-		box.img metadata.json Vagrantfile
+		box.img metadata.json Vagrantfile || err "failed to create .box file"
 	exit 0
 fi
 
-echo "[ERROR]: debian-13-64-vagrant.box already exists"
-exit 1
+err "debian-13-64-vagrant.box already exists"