<script type="module">
// Import the functions you need from the SDKs you need
import { initializeApp } from "https://www.gstatic.com/firebasejs/9.6.7/firebase-app.js";

// https://firebase.google.com/docs/web/setup#available-libraries

// Your web app's Firebase configuration
// For Firebase JS SDK v7.20.0 and later, measurementId is optional
const firebaseConfig = {
  apiKey: "AIzaSyBMvdbhmWerye_LNJEu8UL4UWbKdPs8JzQ",
  authDomain: "hifumidaisuki-8cbbc.firebaseapp.com",
  projectId: "hifumidaisuki-8cbbc",
  storageBucket: "hifumidaisuki-8cbbc.appspot.com",
  messagingSenderId: "695916535200",
  appId: "1:695916535200:web:20171e57229de95ba058c5",
  measurementId: "G-1GR5ECHWHV"
};

// Initialize Firebase
const app = initializeApp(firebaseConfig);

const db = firebase.firestore()
db.collection('student').get().then((결과) => {
  console.log(결과)
})
</script>

"Firebase: No Firebase App '[DEFAULT]' has been created" error occurs in const app = initializeApp(firebaseConfig);. What does "No Firebase App '[DEFAULT]'" mean?