When a domain response is unparseable, there is nothing in the prometheus scrape to indicate it

[Toyam Cox]

To be specific, the parse function returns -1, err instead of days, nil, and this means, ultimately, the monitoring Prometheus instance won't necessarily tell me that the domain is missing.

Perhaps a separate metric should be exported for "Was unable to parse"?

Would a patch implementing this be considered?

[Vincent Palmer]

A patch for this would be welcome yeah.