karma.bin-should-fail --check-config
! stdout .
cmp stderr stderr.txt

-- stderr.txt --
level=error msg="Execution failed" error="failed to unmarshal configuration: 1 error(s) decoding:\n\n* error decoding 'Silences.Expired': time: invalid duration \"abc\""
-- karma.yaml --
alertmanager:
  servers:
    - name: default
      uri: https://127.0.0.1:9093
silences:
  expired: abc
