Improve error messages

[Lasse Rosenow]

When using typst, the error messages received by the biblatex crate are not good yet.

For example this code:

@article{asdf,
  month     = {Sep--Oct},
}

Produces the following error in typst:

Failed to parse BibLaTeX file (test.bib:1: invalid number)

In issue typst/typst#2849 I was informed, that this partially relies on the biblatex crate not yet being able to return good error messages.

This issues purpose is to track this :)