Comment 0 for bug 1863367

A charm is possible to deploy with invalid metrics.yaml:

metrics:
  dead=beef=cafe:
    type: gauge
    description: Some strange metric

As far as I can tell, only basic YAML key validation is done by the YAML parser
https://github.com/juju/charm/blob/v6/metrics.go#L78-L120

Relevant discussion:
https://github.com/canonical/operator/pull/140#discussion_r379481923