Reactjs Firestore的React钩子类型不正确

我有一个用于查询特定Firebase Firestore集合/文档的自定义钩子

import { useContext, useEffect, useState } from 'react';

import { FirebaseContext } from 'providers/Firebase/FirebaseContextProvider';

const useFireStore = (
  collection: string,
  doc: string,
  loadingDelay: number = 0,
) => {
  const { firestore } = useContext(FirebaseContext);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState(null);
  const [document, setDocument] = useState<
    firebase.firestore.DocumentData | undefined
  >();

  useEffect(() => {
    setLoading(true);
    setDocument(undefined);
    const docRef = firestore.collection(collection).doc(doc);
    docRef
      .get()
      .then(doc => {
        setDocument(doc.data());
        setTimeout(() => {
          setLoading(false);
        }, loadingDelay);
      })
      .catch(e => {
        setError(e);
        setLoading(false);
      });
  }, [collection, loadingDelay, doc, firestore]);

  return [document, loading, error];
};

export default useFireStore;

当我在钩子中的

const[document，setDocument]=useState

中将鼠标悬停在

document

上时，我看到

document

类型将是：

const文档：firebase.firestore.DocumentData |未定义

但是，当我将鼠标移到组件中的

const[details，loading，error]=…

中的

document

上时，我看到可能的类型如下：

const详细信息：boolean | firebase.firestore.DocumentData | null |未定义

---

这可能是从哪里来的

boolean

或

null

？

我通过键入

useFireStore

钩子的返回来解决这个问题，例如：

const useFireStore = (
  collection: string,
  doc: string,
  loadingDelay: number = 0,
): [firebase.firestore.DocumentData | undefined, boolean, Error | null] => {
...
}

const useFireStore = (
  collection: string,
  doc: string,
  loadingDelay: number = 0,
): [firebase.firestore.DocumentData | undefined, boolean, Error | null] => {
...
}