title: Property 'XXX' does not exist on type 'CombinedVueInstance<Vue, {}, {}, {}, Readonly<Record<never, any>>>'
body: <p>I created a vue component with TypeScript, and I'm getting this error in <code>data()</code> and in <code>methods()</code>:</p>
  
  <pre><code>Property 'xxx' does not exist on type 'CombinedVueInstance&lt;Vue, {},
  {}, {}, Readonly&lt;Record&lt;never, any&gt;&gt;&gt;'.
  </code></pre>
  
  <p>For example:</p>
  
  <pre><code>33:18 Property 'open' does not exist on type 'CombinedVueInstance&lt;Vue, {}, {}, {}, Readonly&lt;Record&lt;never, any&gt;&gt;&gt;'.
      31 |         methods: {
      32 |             toggle: function () {
    &gt; 33 |                 this.open = !this.open
         |                  ^
      34 |                 if (this.open) {
      35 |                     // Add click listener to whole page to close dropdown
      36 |                     document.addEventListener('click', this.close)
  </code></pre>
  
  <p>This error also shows any time <code>this.close()</code> is used. </p>
  
  <p>This is the component:</p>
  
  <pre><code>&lt;script lang='ts'&gt;
      import Vue from 'vue';
      import axios from 'axios'
      export default Vue.extend({
          data: function () {
              return {
                  open: false
              }
          },
          computed: {
              profilePath: function () {
                  return "/user/" + this.$store.state.profile.profile.user.id
              }
          },
          methods: {
              toggle: function () {
                  this.open = !this.open
                  if (this.open) {
                      // Add click listener to whole page to close dropdown
                      document.addEventListener('click', this.close)
                  }
              },
              close: function () {
                  this.open = false;
                  document.removeEventListener('click', this.close)
              }
          }
      })
  &lt;/script&gt;
  </code></pre>
  
  <p>What is causing this error? It seems to still build in development with the errors, but they are causing issues when I deploy to production.</p>