fix: Manifest folder index loop

[speeddragon]

If a manifest contains as an index key a path with subfolders (/), this will trigger a loop on the server side until the connection times out.

Res structure will be:

#{
  <<"folder"> => 
    #{
      <<"subfolder">> => 
        #{
          <<"subsubfolder">> => {link, ...}
        }
    }
}