我正在做一个关于 React Hooks 和获取数据的教程。这是我用来获取客户并将其映射到列表中的组件：

const useFetch = (url: string) => {
  const [customers, setCustomers] = useState<null | []>(null);
  const [loading, setLoading] = useState(true);

  // Similiar to componentDidMount() and componentDidUpdate()
  useEffect(() => {
    const fetchData = async () => {
      const result = await axios(url);
      setCustomers(result.data);
      setLoading(false);
    };
    fetchData();
  });

  return { customers, loading };
};

const url = 'https://jsonplaceholder.typicode.com/users';

export const LatestCustomers: React.FC<Props> = ({
  description
}: Props): JSX.Element => {
  const { customers, loading } = useFetch(url);

  return (
    <Container>
      {loading ? (
        <div>...Loading...</div>
      ) : (
        <tr>
          {customers.map(customer => (
            <div key="user.id">{customer.name}</div>
          ))}
        </tr>
      )}
    </Container>
  );
};

这样，我得到了错误：

Object is possibly 'null'.  TS2531

    108 |               ) : (
    109 |                 <tr>
  > 110 |                   {customers.map(customer => (
        |                    ^
    111 |                     <div key="user.id">{customer.name}</div>
    112 |                   ))}
    113 |                 </tr>

我该如何解决这个问题？