cast's type does not support undefined or bigint

[reconbot]

I'm migrating from a system where null values are represented as undefined in JS. cast has no issue doing this for us, however it's type has undefined missing from it. Same for the example with BigInt. The type should probably be unknown or any.

[iheanyi]

Thanks for reporting this, you're right that it'd be a better return type. We're gonna take a look at these.