我正在尝试在React中实现错误边界。但由于某种原因，它不起作用。代码如下：

• 错误边界.js*

import React from 'react';

class ErrorBoundary extends React.Component {
  // Equivalent to:
  // const [hasError, setHasError] = useState(false);
  constructor(props) {
    super(props);
    this.state = { hasError: false };
  }

  static getDerivedStateFromError() {
    return { hasError: true };
  }

  componentDidCatch(error, errorInfo) {
    console.error(error);
    console.info({ errorInfo });
  }

  render() {
    if (this.state.hasError) {
      return this.props.fallback || null;
    }

    return this.props.children;
  }
}

export default ErrorBoundary;

• Counter.js*

import React from 'react';

const Counter = ({ user }) => {
  if (!user) {
    throw new Error('Error Some');
  }

  return <div>{user.toUpperCase()}</div>;
};

export default Counter;

• App.js*

import React from 'react';
import ErrorBoundary from './ErrorBoundary';
import Counter from './Counter';

function App() {
  return (
    <ErrorBoundary fallback={<div>this is fallback UI</div>}>
      <Counter />
    </ErrorBoundary>
  );
}

export default App;

下面是live代码。