Use named exports

src/App.tsx

@@ -1,11 +1,9 @@
 import React from 'react';
 
-function App() {
+export function App() {
   return (
     <div>
     Hello, world!
     </div>
   );
 }
-
-export default App;

src/index.tsx

@@ -1,7 +1,7 @@
 import React from 'react';
 import ReactDOM from 'react-dom';
 import './index.css';
-import App from './App';
+import { App } from './App';
 
 ReactDOM.render(
   <React.StrictMode>