记一个Vuex的报错：Object(...) is not a function

main.js中引入正确的写法应该是 from "vuex"

import store from 'vuex';

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

(但很疑惑的是之前我写的是 from "./store" 成功运行了......)