title: access state in setup on methods Vue 3 got error TS doesn't exist
body: <p>I am using Vue 3 and TS, I have some states in the <code>Setup</code> function which like this</p>
  <pre><code>export default defineComponent({
    setup() {
      const isLoadingSendData = ref(false)
  
      return { isLoadingSendData }
    
    },
    methods: {
      disableBtn(): boolean {
         // on Webstorm i got error: TS2339: Property 'isLoadingSendData' doesn't exist 
         // on type 'disableBtn(): boolean'
         if(this.isLoadingSendData) {
           return // do something
         }
         return // do something
      }
  
    }
  })
  </code></pre>
  <p>that is just an example I can give for a case, the <code>this.isLoadingSendData</code> got error red on my IDE, does anyone know why ??</p>