That didn't solve the problem. If I comment out the line where it descends a sub-directory (and calls itself):

## dir, decend
if (-d $file) {

        ## sub-directory files
        #$files = _list_files($file, $files);
}
[download]

It works. Well, it returns all the files in the cwd as expected. But when that line is not commented out, if it finds a sub directory, it never returns to finish listing the files in the parent (the one we started in).