I cannot index "status.actions.my_webhook.last_execution.successful" in .watcher-history-*

this is related Alert when watcher is in error state - .watcher_history topic I raised a few days ago.

All I am looking for is a programmatic method of getting alerted if a watcher is in error state. At the moment I found a field that is changing when a watcher error happen so I am trying to come up with a query first before creating an alert.