Need help with emscripten port

[brson]

We could definitely implement a different unwinding scheme on the Rust side. Another variation is return-based unwinding, where every call returns an implicit flag indicating the unwinding path. That would not use the js unwind machinery at all. I’ve always wanted such an alternate unwinding scheme anyway, though I can’t remember the other use-cases offhand… certainly it’s useful in places where zero-cost unwinding doesn’t exist (like emscripten).