Error when clicking on unmanaged for multi site setup

I've also just attempted to use this on a multi-site (multsite) setup and can confirm that this is still an issue. I will look at the code and see if there's a way to check all subfolders in the /sites directory.

This issue is in src/UnmanagedFilesService.php on line 173 where:
$public_dir = $this->state->get('file_public_path', 'sites/default/files');
is declared. This would need to be done in a loop for all subdirectories - eg. /sites/*/files

Alternatively there could be an admin screen that allows us to specify which files directories we want to search in that then gets saved as an array variable that can be looped through in this code.