useEffect(() => {
  const fetchData = async () => {
    try {
      setLoading(true);
      const response = await fetch('/api/data');
      if (!response.ok) throw new Error('Network response was not ok');
      const json = await response.json();
      setData(json);
    } catch (err) {
      setError(err.message);
    } finally {
      setLoading(false);
    }
  };
  fetchData();
}, []);