Problem
Paths in notebooks/<path>
url routes that are directories and not notebooks will show an error instead of redirecting to tree/<path>
urls.
This behavior differs from Classic Notebook (notebook<7) where directory path links under notebooks/<path>
simply redirect to a tree/<path>
link and display the directory nicely.
Proposed Solution
Paths in notebooks/<path>
urls that are directories should redirect nicely to tree/<path>
urls.
#7446 provides a solution to this.