fix: unwrap refs returned by data

[pikax]

fix #385

I have a few concerns here, because the unwrapping will create a new object everytime:

const myObject = { a: 1}

const vm = new Vue({     data() {
        return {
          myObject,
        }
      },
    }).$mount()

vm.myObject === myObject; // this will always be false

Not sure how much of a deal breaker this might be, one way to do this is only unwrap if there's a ref anywhere in the object.

The reason we create a new object is because we don't want to mutate the original object the user is using in the setup, because that will lead to some unexpected bugs

[antfu]

Thanks for make PR so fast as always!

Just tested out with vue-next, I am surprised to see that vue-next does handle ref in data. (which makes setup and data almost the same to me). Since vue-next does that, I think it's good to have it in this plugin as well.

About the deep cloning, I think it's ok in most of the common cases. One thing I am worried about is the performance impact when passing a huge object. That would require users to use Object.freeze for them.

[pikax]

My concerns is using the template to change the object values :/

[antfu]

template to change the object values

Sorry, I can't imagine a case right out of my mind. Can you show me an example about that?

[pikax]

The case I was thinking was this: https://github.com/vuejs/composition-api/pull/387/files#diff-de44c4f0babbf8fdd103f1756b4b7dd9R748

But seems to work just fine