相关疑难解决方法(0)

我刚刚开始学习React Native，在youtube上观看视频时，遇到了一个我不明白的错误。我认为我的错误是由 firebase.js 文件引起的。`

firebase.js

import * as firebase from "firebase"
import "firebase/firestore"
import "firebase/auth"


const firebaseConfig = {
    apiKey: "",
    authDomain: "",
    projectId: "",
    storageBucket: "",
    messagingSenderId: "",
    appId: ""
  };

let app

if (firebase.apps.length === 0){
    const firebaseApp = firebase.initializeApp(firebaseConfig)
} else {
    app = firebase.app()
}

const db = app.firestore()
const auth = firebase.auth()

export { db, auth }

错误

TypeError: undefined is not an object (evaluating 'app.firestore')
at node_modules\react-native\Libraries\LogBox\LogBox.js:148:8 in registerError
at node_modules\react-native\Libraries\LogBox\LogBox.js:59:8 in errorImpl
at …