To me, one thing missing from most popular web languages is the single best part of Rust: A well-defined handling of the non-happy path.

I'm talking about things like exhaustive "switches", built-in, ENFORCED handling of "missing" values (null, undefined), and finally useful error handling.

I actually don't need any of the baremetal features of Rust. It's just that most of it's "zero-cost" abstractions are still far superior to those of other languages.