Still print error messages on unset variables.

Author: YtvwlD

bin/backup

@@ -2,9 +2,9 @@
 set -e # Exit if a command exists with an error.
 set -o pipefail # If any command in a pipe exits with an error, treat the whole pipe as failed.
 set -u # Fail if a variable is used, but not defined.
-[ -z "${BACKUP_NAME}" ] && { echo "error: BACKUP_NAME not set"; exit 1; }
-[ -z "${BACKUP_GPG_KEY_ID}" ] && { echo "error: BACKUP_GPG_KEY_ID not set"; exit 1; }
-[ -z "${BACKUP_SSH_DESTINATION}" ] && { echo "error: BACKUP_SSH_DESTINATION not set"; exit 1; }
+[ -z "${BACKUP_NAME:-}" ] && { echo "error: BACKUP_NAME not set"; exit 1; }
+[ -z "${BACKUP_GPG_KEY_ID:-}" ] && { echo "error: BACKUP_GPG_KEY_ID not set"; exit 1; }
+[ -z "${BACKUP_SSH_DESTINATION:-}" ] && { echo "error: BACKUP_SSH_DESTINATION not set"; exit 1; }
 BACKUP_INTERVAL=${BACKUP_INTERVAL:-1h}
 BACKUP_SSH_REMOTE_DIRECTORY=${BACKUP_SSH_REMOTE_DIRECTORY:-backup}