We're seeing this as well.
There are a couple of us on Drupal slack that want to get symlinks working for the Storybook module, and this issue came up. Could you clarify your use case? If you are referring to you SDC components via symlink, it seems like you'd want the module to follow symlinks. There are definitely a few parts of the module and underlying libraries that are written to exclude symlinked files. From what I've seen, it looks like on of the iterators being used just doesn't know how to handle symlinked directories, and that's what is causing the error.
Changing line ~92 to:
$it = new \RecursiveIteratorIterator($filter, \RecursiveIteratorIterator::LEAVES_ONLY, $flags);
got past the immediate error, but then you run into the rest of the code not expected symlinked paths.
Patch
ashooner → created an issue.