`RefCell` inside `Arc`

[Jonathan Wang]

https://github.com/axiom-crypto/halo2-wasm/blob/b02413ca50c1914a5b39f0768ebd3d98a15cb84c/src/lib.rs#L73

Usually one uses either Rc<RefCell> if it is not intended to be thread-safe, or Arc<Mutex> if it is supposed to be thread-safe (the Mutex locks until the given thread gets access to the object).

What is the intended use case here?

[Roshan]

Not intended to be thread-safe -- changed to Rc<RefCell> in a733ab8. Thanks.