Using VueJS + FeathersJS + Feathers-Vuex, getting this error: Uncaught TypeError: vue__WEBPACK_IMPORTED_MODULE_0__.default is undefined

Here is the error:

Uncaught TypeError: vue__WEBPACK_IMPORTED_MODULE_0__.default is undefined
    <anonymous> index.js:7
    js app.js:96
    __webpack_require__ app.js:397
    fn app.js:643
    <anonymous> main.js:6
    js app.js:74
    __webpack_require__ app.js:397
    __webpack_exports__ app.js:1531
    O app.js:446
    <anonymous> app.js:1532
    <anonymous> app.js:1534

and here is my index.js (from the documentation for feathers-vuex)
// src/store/index.js
import Vue from 'vue'
import Vuex from 'vuex'
import { FeathersVuex } from '../feathers-client'
import auth from './store.auth'

Vue.use(Vuex)
Vue.use(FeathersVuex)

const requireModule = require.context(
  // The path where the service modules live
  './services',
  // Whether to look in subfolders
  false,
  // Only include .js files (prevents duplicate imports`)
  /\.js$/
)
const servicePlugins = requireModule
  .keys()
  .map(modulePath => requireModule(modulePath).default)

console.log('1: ', requireModule.keys())
console.log('2: ', servicePlugins)

export default new Vuex.Store({
  state: {},
  mutations: {},
  actions: {},
  plugins: [...servicePlugins, auth]
})

Also, here is my main.js import Vue from 'vue' import VueCompositionApi from '@vue/composition-api' Vue.use(VueCompositionApi)

import App from './App.vue'
import router from './router'
import store from './store'

import './assets/styles/base.css'
import './assets/styles/chat.css'

Vue.config.productionTip = false

new Vue({
  router,
  store,
  render: h => h(App)
}).$mount('#app')

It seems the problem is with @vue/composition-api but I've been digging for days and cannot find out how to resolve this issue. I am trying to rebuild the feathers-vuex-chat from the FeathersJS site using the newest version of VueJS, FeathersJS and Feathers-Vuex. Any help would be greatly appreciated!