[2526] vuex mapGetters not working.

I get error when i try use mapGetters

My store/index.js

import Vuex from 'vuex'
import modules from './modules'

export default () => {
  return new Vuex.Store({
    modules
  })
}

store/modules/index.js

import homePage from './homePage'

export default {
  homePage
}

store/modules/homePage.js

import getApi from '@/plugins/prismicApi'
import { GET_HOME_PAGE } from '../mutationTypes'

const state = {
  homePage: null
}

const getters = {
  homePage: state => state.homePage
}

const actions = {
  async getHomePage ({ commit }) {
    const api = await getApi()
    const homePage = await api.getSingle('home_page')
    commit(GET_HOME_PAGE, homePage.data)
  }
}

const mutations = {
  [GET_HOME_PAGE] (state, payload) {
    state.homePage = payload
  }
}

export default {
  state,
  getters,
  actions,
  mutations
}

I do not want namespaced modules, so I use this way of defining modules. I try set namespaced: false, but it's not help. And now my index.vue

 import { mapGetters } from 'vuex'

export default {
  name: 'index',
  async fetch ({ store }) {
    return store.dispatch('getHomePage')
  },
  computed: {
    ...mapGetters('homePage')
  }
}