1. In the sidebar, open the File System view.
2. Navigate to a directory for which you don't have read access.
   The view will display the directory's name in its title but no contents. Since there is no ".." entry, you can't navigate out of the directory. The last resort is "Choose Folder..." from the context menu.

Creator should either display a note that the directory is not readable and a way back out or not enter such directories at all.