OptionalType check

Currently, I need to explicitly convert an optional type to its original type even though the variable can’t be optional in that branch.

(if (not (is-none? price))
      (contract-call! token transfer receiver (expects! price invalid-price-err))

Is it possible to deduce that in this case price is a real type, not an optional one?

Copied over to https://github.com/blockstack/clarity-js-sdk/issues/42