@vuepress-reco/style-default/lib/client/composables/useInstance.js

It is default type of vuepress-theme-reco.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.useInstance = void 0;
const vue_1 = require("vue");
function useInstance() {
    const vm = vue_1.getCurrentInstance();
    if (!vm)
        throw new Error('must be called in setup');
    const instance = vm || {};
    return instance;
}
exports.useInstance = useInstance;