#課題
下記のようなエラーが表示される

Unhandled Rejection (Error): Federation requires either a User Pool or Identity Pool in config
AuthClass.<anonymous>
C:/Users/higuz/Documents/src/Auth.ts:1749
  1746 | case 2:
  1747 |     _b.trys.push([2, 6, , 7]);
  1748 |     return [4 /*yield*/, this._oAuthHandler.handleAuthResponse(currentUrl)];
> 1749 | case 3:
       | ^  1750 |     _a = _b.sent(), accessToken = _a.accessToken, idToken = _a.idToken, refreshToken = _a.refreshToken, state = _a.state;
  1751 |     session = new CognitoUserSession({
  1752 |         IdToken: new CognitoIdToken({ IdToken: idToken }),
View compiled
▶ 5 stack frames were collapsed.
onClick
C:/Users/higuz/Documents/fingers-crossed/src/App.js:17
  14 |       <p>
  15 |         Edit <code>src/App.js</code> and save to reload.
  16 |       </p>
> 17 |       <button onClick={() => Auth.federatedSignIn()}>Sign In</button>
     | ^  18 |     </header>
  19 |   </div>
  20 | )

#解決策
index.js にconfigを追加する。

index.js

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import * as serviceWorker from './serviceWorker';
import Amplify from 'aws-amplify' // 追記
import config from './aws-exports' // 追記
Amplify.configure(config) // 追記