* Fixes runtime from bookshelves being maploaded in after SSlibrary is done instantiating (#69425)
* Fixes runtime with bookshelves loading.
- If a bookshelf is maploaded after the library subsystem is instantiated, it runtimes due to shelves_to_load being null, and no books are loaded. So, if a bookcase is maploaded after SSinit is done initializing, just load the shelf in init.
* Needs to be asyncronous.
* Fixes runtime from bookshelves being maploaded in after SSlibrary is done instantiating
Co-authored-by: MrMelbert <51863163+MrMelbert@users.noreply.github.com>