问'CombinedVueInstance<Vue，{}，Readonly<Record<never，any>>>‘类型上不存在属性'XXX’

EN

Property 'xxx' does not exist on type 'CombinedVueInstance>>'.

33:18 Property 'open' does not exist on type 'CombinedVueInstance>>'.
    31 |         methods: {
    32 |             toggle: function () {
  > 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)

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)
            }
        }
    })