The remote command returns a failure error code (87) and Net::OpenSSH sets the error flag to OSSH_SLAVE_CMD_FAILED. Then, in...

$ssh->error and
    die "remote ls command failed: " . $ssh->error;
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The die instruction is actually invoked and the print sentences below never reached.

Instead, write it as follows:

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";
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Note also that in Perl, (@array, $scalar) = whatever() is never what you want because @array "eats" all the values returned by whatever(), and $scalar always becomes undef.

That's the reason why Net::OpenSSH->capture2(...) returns just two scalars in all the occasions, while Net::OpenSSH->capture(...) can be more clever and return lines in list context or one scalar with the full output in scalar context.