Mismatched Filetree Item Hrefs and Shelf IDs

[Corban-Lee]

Clicking on a filetree item should scroll the page to the shelf with the matching ID. This sometimes works, but other times does not.

This is caused because the ID is constructed differently for the filetree and shelves, also some filetree items are constructed for non-existing shelves – these should maybe show a pop-up message or act as the dropdown button?