protected function jsonErrorMessage($errorNumber)
    {
        $messages = array(
            JSON_ERROR_NONE => 'No error has occured',
            JSON_ERROR_DEPTH => 'The maximum stack depth has been exceeded',
            JSON_ERROR_STATE_MISMATCH => 'Invalid or malformed JSON',
            JSON_ERROR_CTRL_CHAR => 'Control character error, possibly incorrectly encoded',
            JSON_ERROR_SYNTAX => 'Syntax error',
            JSON_ERROR_UTF8 => 'Malformed UTF-8 characters, possibly incorrectly encoded'
        );
        return isset($messages[$errorNumber]) ? $messages[$errorNumber] : 'Unknown JSON encoding error';
    }