Don't log error on missing BIND 9 stats
agent-bind9-2_1 | ERRO[2020-06-10 18:00:04]prombind9exporter.go:663 no 'qtypes' in response:
agent-bind9-2_1 | ERRO[2020-06-10 18:00:04]prombind9exporter.go:663 no 'nsstats' in response:
agent-bind9_1 | ERRO[2020-06-10 18:00:05]prombind9exporter.go:663 no 'qtypes' in response:
agent-bind9_1 | ERRO[2020-06-10 18:00:05]prombind9exporter.go:663 no 'nsstats' in response:
When certain statistics are not reported by the statistics-channel, this should be omitted with a notice not an error.