Comment by pornel

sqlite also has some runtime checks that are expected to be always true or always false, and solves that by using a custom macro that removes these branches during branch coverage test.

The same would be possible in Rust. Everything that could panic has a non-panicking alternative, and you could conditionally insert `unreachable_unchecked()` to error handling branches to remove them. That wouldn't be most idiomatic, but SQLite's solution is also a custom one.