RI: The sentinel sub-folder (/media/sd-card/cloudsync/sentinel/) is created by the Watchdog._init_() constructor in cloudsync/utils/watchdog.py - it runs os.makedirs(sentinel_dir, exist_ok=True) at construction time, so the folder exists before any sentinel file gets written.
For default cases (throughout this unit), we either need a s/w fault (because this should never happen and indicates memory corruption) or a comment noting it is ok to ignore invalid cases (commands in this case).
