Cannot use data properties in script when using Vue.extend

[Cy-Tek]

Describe the bug
When I have a template that is not using the class style of component, the parser complains about accessing data from either methods or computed properties. It does not complain when I convert the template to using vue-property-decorator

To Reproduce
Steps to reproduce the behavior:

1. Make a component with a script section like

   <script lang="ts">
   import Vue from 'vue'
   
   export default Vue.extend({
     name: 'Test',
     data() {
       return {
         str: 'Hello world'
       }
     },
     computed: {
       getStr(): string {
         return this.str
       }
     }
   })
   </script>

2. Run nuxt-ts dev
3. See error

Expected behavior
I should be able to access the properties on data from either the computed or methods properties without using vue-property-decorator

Screenshots
Example:

[kevinmarrec]

@Cy-Tek This issue may happen when you have a computed property that has implicit return type, making other return types buggy.

Minimal component following your code

Issue happenning cause return type of authors is implicit

Fixed by providing the correct return type (IAuthor[]):

I suspect that your component code contains somewhere an implicit typing that make the issue happens.

[kevinmarrec]

@Cy-Tek Can I close ?