Error when I use Version 2.0 in CLI because of HTTP_USER_AGENT

[handrasl]

I would like to check the transactions' statuses that are in progress in a CLI command.
BarionClient throws an error because of there is no HTTP_USER_AGENT key under $_SERVER variable when I use CLI.

$userAgent = $_SERVER['HTTP_USER_AGENT'];
if ($userAgent == "") {

I think it would be better that way.

$userAgent = $_SERVER['HTTP_USER_AGENT']  ?? null;
if (empty($userAgent)) {