Type issue when initializing a ref() with an object that includes router types

[JammingBen]

I'm currently facing an issue where TS complains about incorrect types when initializing a ref() with an object that includes a property of type RouteLocation.

The code looks something like this:

type FooType = {
  name: string,
  to?: RouteLocation
}

const foo: FooType = { name: 'test' };
const bar: Ref<FooType> = ref(foo)

Now TS is complaining that foo isn't assignable to the type FooType. It seems to come down to this issue: Types of property 'path' are incompatible. Type 'unknown' is not assignable to type 'undefined'.

Also, I only encounter this error with vue-router versions >= 4.3.0. Anyone got an idea why this is happening?

Reproduction: Vue SFC Playground (see app.vue file)

[posva]

You should pass the type param to ref directly: const bar = ref<FooType>(foo)

[JammingBen]

I thought about that and while the error does indeed disappear, it's but only because bar is actually not of type FooType in this case. So it becomes an issue when e.g. passing bar to a function that expects a parameter of type FooType: Check here.

I guess the difference is because Vue is unwrapping refs when resolving them. Also see https://github.com/orgs/vuejs/discussions/9564#discussioncomment-7518938.