Accessing Subfolder that does not exist render 404 Error

[bivanalhar]

Issue

When user accesses a non-existent folder /courses/<course-id>/materials/folders/<non-existent-folder-id>, they will be presented with an empty folder instead of a 404 page.

Proposed solution

Propose to show a screen that is similar to non-existent files as shown below:

/courses/<course-id>/materials/folders/<folder-id>/files/<non-existent-file-id>