Null pointers (and then UB) when creating two Sorts with the same name

[shelvacu]

repro:

use z3::Sort;

fn main() {
    let cfg = z3::Config::new();
    let ctx = z3::Context::new(&cfg);

    let res1 = Sort::enumeration(
        &ctx,
        "SameNameSort".into(),
        &["A".into(), "B".into(),]
    );
    dbg!(&res1);
    let res2 = Sort::enumeration(
        &ctx,
        "SameNameSort".into(),
        &["C".into(), "D".into(),]
    );
    dbg!(&res2);
}

This manages to show the issue without triggering any UB, but doing anything interesting with res2 gives a nullptr exception

I'm not sure what exactly is supposed to happen, but at the very least this should panic!