languages key is not excluded with JSON converter

[Techbrunch]

php countries.php convert -x cioc -x callingCode -x capital -x altSpellings -x region -x subregion -x demonym -x landlocked -x borders -x area -x latlng -x ccn3 -x tld -x translations -x name -x languages -x cca3 -x currency

Expected:

[{"cca2":"AW"},
{"cca2":"AF"},
{"cca2":"AO"},
{"cca2":"AI"},
{"cca2":"AX"},
{"cca2":"AL"},
{"cca2":"AD"},
{"cca2":"AE"},
{"cca2":"AR"},
{"cca2":"AM"},
{"cca2":"AS"},
{"cca2":"AQ"},
...

Result:

[{"cca2":"AW","languages":{}},
{"cca2":"AF","languages":{}},
{"cca2":"AO","languages":{}},
{"cca2":"AI","languages":{}},
{"cca2":"AX","languages":{}},
{"cca2":"AL","languages":{}},
...