Avoid panics for untrusted data

[nyurik]

Hi, I would like to use your code with the https://github.com/stadiamaps/pmtiles-rs but it seems invalid coordinates may panic the code. Would it be possible to return Option<...> in the cases where the code would panic? The common problem we may face is user-supplied invalid data, so we should avoid panicking in those cases. Thanks!

[becheran]

It should not be too hard to implement this. Won't have time to look at this before end of next week.