리액트 메타마스크 연동관련

제가 제 프로젝트 app.js에 넣은 코드입니다

import React, { Component } from 'react';
import logo from './logo.svg';
import './App.css';
import Web3 from 'web3';

class  App extends Component {

  componentDidMount = async () => {
    await this.initWeb3();
  }
  initWeb3 = async () => {
    if (window.ethereum) {
      console.log('recent mode');
      this.web3 = new Web3(window.ethereum);
      try {
          // Request account access if needed
          await window.ethereum.enable();
          // Acccounts now exposed
          //this.eth.sendTransaction({/* ... */});
      } catch (error) {
          // User denied account access...
          console.log('user denied account access error: ' + error);
      }
  }
   // Legacy dapp browsers...
    else if (window.web3) {
     console.log('legacy mode');
       this.web3 = new Web3(window.web3.currentProvider);
       // Acccounts always exposed
        //web3.eth.sendTransaction({/* ... */});
   }
    // Non-dapp browsers...
    else {
     console.log('Non-Ethereum browser detected. You should consider trying MetaMask!');
   }
 }
 render(){
  return (
    <div className="App">
      <header className="App-header">
        <img src={logo} className="App-logo" alt="logo" />
        <p>
          Edit <code>src/App.js</code> and save to reload.
        </p>
        <a
          className="App-link"
          href="https://reactjs.org"
          target="_blank"
          rel="noopener noreferrer"
        >
          Learn React
        </a>
      </header>
    </div>
  );
 }
}

export default App;