There are some languages that can be formally verified, and have themselves been formally verified.
Formal verification is a complete pain in the ass to do and there's a reason it's mostly done only in the most critical of systems, but if a program passes 100% formal validation, you're as close to crash free as you can possibly be.
I believe Ada and some other lesser used language sport well supported formal verification methods. You won't be able to use C/C++/Java/Rust it you're going for 100% formal verification though. There are attempts to bring the concepts to more commonly used languages (Frama-C, for example) but in my experience they're stuck in PhD-ware hell, great for writing papers but terrible for writing actual software.
Frama-C is used in production to meet normative requirements for critical software at least at Airbus (DO-178C), THALES (CC EAL6/7), EDF (ISO 60880). I think that they use actual software in production.
Formal verification is a complete pain in the ass to do and there's a reason it's mostly done only in the most critical of systems, but if a program passes 100% formal validation, you're as close to crash free as you can possibly be.
I believe Ada and some other lesser used language sport well supported formal verification methods. You won't be able to use C/C++/Java/Rust it you're going for 100% formal verification though. There are attempts to bring the concepts to more commonly used languages (Frama-C, for example) but in my experience they're stuck in PhD-ware hell, great for writing papers but terrible for writing actual software.