React: What is React error handling?

1class ErrorBoundary extends React.Component {
2  state = { error: null };
3  static getDerivedStateFromError(error) { return { error }; }
4  render() {
5    if (this.state.error) return <ErrorFallback error={this.state.error} />;
6    return this.props.children;
7  }
8}

1function DataLoader() {
2  const [error, setError] = useState(null);
3  const [data, setData] = useState(null);
4  useEffect(() => { fetchData().then(setData).catch(setError); }, []);
5  if (error) return <ErrorMessage error={error} />;
6  if (!data) return <Spinner />;
7  return <DataView data={data} />;
8}