Type error when Template interpolation service in combination with templateProps is set to true

[dietergoetelen]

• [x] I have searched through existing issues
• [x] I have read through docs
• [x] I have read FAQ

Info

• Platform: Win
• Vetur version: 0.28.0
• VS Code version: 1.49.1

Problem

Vetur cannot find the type when using PropType<User> in the referenced component. TemplateInterpolationService is set to true as well as validate templateProps.

Reproducible Case

1. Use "vetur.experimental.templateInterpolationService": true,
2. Use "vetur.validation.templateProps": true,
3. Create file Hello.vue

   
   <template>
   <div>
   Hello, {{ user.name }}
   </div>
   </template>

4. Create file `Greeting.vue`

This works fine if I use an anonymous type. Tried to trick the compiler to omit the actual type without any success.

type User = {name: string}

const trick = () => () => undefined as unknown as {

}

const TrickedUser = trick()

export default defineComponent({ props: { user: { type: Object as PropType<ReturnType>, required: true } }, setup () { return {} } })

This gives the following component type props: 
![image](https://user-images.githubusercontent.com/1385245/93986513-ba398c00-fd86-11ea-9159-217cf9196446.png)

But vetur is still complaining, in this case it cannot find `TrickedUser`

[cexbrayat]

I ran into something very similar using VTI@0.0.13

Repro: https://github.com/cexbrayat/vti-async

yarn
npx vti@0.0.13 diagnostics

Results in:

====================================
Getting Vetur diagnostics
Loading Vetur in current directory: /Users/ced-pro/Code/vue/vti-async
Loaded bundled typescript@4.0.3.
Vetur initialized
====================================

Getting diagnostics from:  [ 'src/App.vue', 'src/components/HelloWorld.vue' ]

File : /Users/ced-pro/Code/vue/vti-async/src/App.vue
Error: Cannot find name 'UserModel'.

====================================

Because the component HelloWorld has a prop defined as:

export default defineComponent({
  name: 'HelloWorld',
  props: {
    user: {
      type: Object as PropType<UserModel>
    }
  }
});