Option '-j' does not proper work with getconfig command

[Custler]

$ tonos-cli -j getconfig 15
Input arguments:
   index: 15
Config p15: {
  "validators_elected_for": 10800,
  "elections_start_before": 5400,
  "elections_end_before": 1350,
  "stake_held_for": 5400
}

But it have to output pure json only