As far as I've seen, it's generally just the WASM modules that crash, and not a full sim crash to desktop (CTD). But considering the WASM modules are usually running all of the aircraft logic, systems, flight control computers, etc. then it tends to mean a complete flight loss since you can't... well... control the aircraft anymore. I'm not sure what kind of automatic restart logic exists for crashed WASM modules, if anything. It would be interesting to see if module crash recovery is possible.