Uncaught ReferenceError: Cannot access '__WEBPACK_DEFAULT_EXPORT__' before initialization

It seems like you're encountering a JavaScript module loading issue, which is often related to circular dependencies or incorrect import/export statements when using webpack.

Here's a potential solution to your problem:

1. Ensure that there are no circular dependencies between your modules. A circular dependency occurs when two or more modules are dependent on each other. This can cause the modules to be loaded in an unexpected order, leading to the error you're seeing.

2. Check that you're exporting App correctly from the ./App file. It should look something like this:

// In your App.js or App.jsx file
import React from 'react';
// ... other imports

class App extends React.Component {
  // ... component code
}

export default App;

1. Make sure that you're importing App correctly in the file where you're trying to use it:

// In the file where you're getting the error
import app from './App';
import cors from 'cors';

app.use(cors());

1. If App is a React component and you're trying to use it as an Express middleware (which seems to be the case since you're calling app.use(cors());), you're mixing up front-end and back-end concepts. cors is a middleware for Express (a Node.js framework), and it should be used in the context of setting up an Express server, not with a React component.

If you're setting up an Express server, your code should look more like this:

// In your server.js or app.js (Node.js context)
const express = require('express');
const cors = require('cors');
const app = express();

app.use(cors());

// ... other middleware and route setup

app.listen(3000, () => {
  console.log('Server running on port 3000');
});

If App is indeed a React component, you don't use app.use(cors()); in the same file. CORS should be configured on your server, not in your React application.

Please double-check your code structure and ensure that you're using the correct imports and exports for your modules. If you continue to have issues, please provide more context or code snippets so that I can give you a more precise solution.