When closing the PDF viewer it tries to load the current folder as PDF

[JammingBen]

Steps to reproduce

1. Upload a PDF file
2. Open the PDF file with the PDF viewer
3. Close the PDF viewer via the button on the top right and check the network tab

A few requests are being made. This happens because the viewer tries to load the current folder as PDF. This is not an issue in most cases, however, there is one exception: Sharing the file via a public link and then opening the public link will instantly open the PDF viewer. Now when closing the viewer it will fail and break all possible redirects happening after (e.g. #9299).