How do I debug failed events from integration rules (queue, firehose, webhooks etc.)?

Per https://faqs.ably.com/what-is-the-difference-between-failed-and-refused-message-statistics , `failed` events in the statistics for queues, firehose, or webhooks mean that the message has been rejected by the external target. Since we can't distinguish between expected and unexpected reasons from external sources, all rejections from external systems such as Reactor targets will show up as 'failed' in the relevant stats section.

Whenever this happens, we publish a message with the reason for the failure (for example, 'POST returned HTTP status 500'), along with metadata such as the rule ID, the message ID that failed, and the channel that the message was sent in, to the log metachannel for the app, `[meta]log`. See https://ably.com/docs/metadata-stats/metadata/subscribe#log for more information on the log metachannel.

You can see these events live by going to the dev console for that app, or use our history API on the log metachannel to see and paginate through past messages on that app (or attach to it with rewind to see the last up-to-100 messages on that metachannel)