Create a type guard for LinkOptions

[RMHonor]

In more complex scenarios, URL paths may come from dynamic sources, e.g. a backend response. In these situations, the data is likely untyped, or loosely typed, where it's unreasonable to keep the external source synchronised with the possible routes.

For example:

const res = await fetch("https://my.links") // return a list of links
const links = (await res.json()).links;

router.navigate({
  to: links[0].to, // no guarantee this route exists
});

A type guard would be able to provide a utility to guarantee that a runtime object satisfies our discrete set of navigation options.

function isValidToOptions<T>(opts: T) T is ToOptions {
  // logic in here to check against registered routes
}

// usage
if (isValidToOptions(dynamicLinkResponse)) {
  navigate(dynamicLinkResponse); // type safe
}

Alternatively, it could throw an error, rather than using the is syntax, and return the valid ToOptions