An extension trait for `Option<T>` and `Result<T, E>` for unwraping the `T`
value, or throwing a JS error if it is not available.
These methods should have a smaller code size footprint than the normal
`Option::unwrap` and `Option::expect` methods, but they are specific to
working with wasm and JS.
On non-wasm32 targets, defaults to the normal unwrap/expect calls.
