执行react-redux项目时遇到此错误。错误：- TypeError:无法读取React-Redux项目中未定义的属性'map‘

import React from 'react';
import { Provider } from 'react-redux';
import { createStore } from 'redux';
import rootReducer from './reducers';

{data.map(item => (
  <div key={item.id}>{item.name}</div>
))}

import { connect } from 'react-redux';

const mapStateToProps = state => ({
  // 将需要的state映射到props中
  data: state.data
});

const mapDispatchToProps = dispatch => ({
  // 将需要的action creator映射到props中
  fetchData: () => dispatch(fetchData())
});

export default connect(mapStateToProps, mapDispatchToProps)(YourComponent);

const initialState = {
  data: []
};

const reducer = (state = initialState, action) => {
  switch (action.type) {
    // 处理相应的action类型，更新state
    default:
      return state;
  }
};