use Net::OpenSSH;
use Net::OpenSSH::Constants qw(:error);

...

my ($output, $errput) = $ssh->capture2({tty => 1}, $xxx);

if ($ssh->error and $ssh->error != OSSH_SLAVE_CMD_FAILED) {
    die "remote ls command failed: " . $ssh->error;
}

print "OUT: $output\n";
print "ERR: $errput\n";
print "RC: $?\n";