I remember a couple of years ago a root exploit in Sudo that was the result of failing to check for a sentinel value, thinking “that is a bug that wouldn’t happen in Rust, even though it isn’t related to memory safety!”

Rust enums are sum types, and imho are one of the few unambiguously good language feature ideas. I miss them any time I use a language where they are not built in. F# is another nice language where they are first class and where I first got familiar with them