Many users of VFS didn't check for nullptr or 0 results leading to
various potential issues, to mitigate this introduce error checking to
VFS by default. The original variants can still be used through the
*Unchecked family of functions.
An NSP (Nintendo Submission Package) is effectively a PFS0 containing
NCAs, there are also tickets and a CNMT file which contains metadata
about updates. The current implementation is very basic and only
support Control and Program NCAs which is enough for loading games.
Support for updates and dlc will be added at a later date.