Looked through library.
user_error('Connection closed by server', E_USER_NOTICE);
It triggers errors. You can handle those errors using http://php.net/manual/en/function.set-error-handler.php
e.g.
// Your file.php
$ssh = new Net_SSH2('10.199.1.7');
$ssh->login('deploy', $key);
// bootstrap.php
// This will catch all user notice errors!!!
set_error_handler ('errorHandler', E_USER_NOTICE)
function errorHandler($errno, $errstr, $errfile, $errline) {
echo 'Error';
// Whatever you want to do.
}