Sensu-go: Metric extraction: a bad line should not abort extraction

[portertech]

We ran into trouble extracting metrics from Kube State Metrics, using the sensu-prometheus-collector plugin and InfluxDB line output.

Expected Behavior

The Sensu Agent will do its best to extract metrics from check output, logging invalid lines.

Current Behavior

The Sensu Agent will abort check output metric extraction if it encounters an invalid line.

https://github.com/sensu/sensu-go/blob/a9f7289efe6107a8ba7c84fc571d2ae6dadf280c/agent/transformers/influx_db.go#L50

[echlebek]

Half enhancement, half bug IMO :)