Cannot find modue default firebase app - firebase

Question

const functions = require('firebase-functions');
const admin = require('firebase-admin');
const firebase = require('firebase/app');
const credentials = require('./credentials.json');
const db = admin.firestore();
const user = require('./http-functions/user-creation')
var config = {
apiKey: "KEY",
authDomain: "ecommerce.firebaseapp.com",
databaseURL: "https://ecommerce.firebaseio.com",
projectId: "ecommerce",
storageBucket: "ecommerce.appspot.com",
messagingSenderId: "ID"
};
firebase.initializeApp(config)
admin.initializeApp({
credential: admin.credential.cert(credentials),
databaseURL: "https://ecommerce.firebaseio.com",
projectId: "ecommerce"
});
exports.addUser = functions.https.onRequest((req, res) => user.addUser(req, res, db, firebase))
I'm importing firebase so that I can use the firebase.auth() to create a new user on cloud functions firestore. But I'm having this error where it says that when I run my firebase deploy:
Error: The default Firebase app does not exist. Make sure you call initializeApp() before using any of the Firebase services.
at FirebaseAppError.FirebaseError [as constructor]
Below is the code for adding a new user
module.exports = {
addUser: function(req, res, db, firebase, admin) {
firebase.auth().createUserWithEmailandPassword(email, password)
.then(userRecord => {
const uid = userRecord.uid;
const email = userRecord.email;
return firebase.firestore()
.collection('users')
.doc(uid)
.set({email: email},
{merge: true});
})
.catch(err => {
console.log(err)
})
}
}

Answer 1

Try assigning the intitializeApp into a const and use it instead of firebase.auth()
Something like:
var config = {
apiKey: "KEY",
authDomain: "ecommerce.firebaseapp.com",
...
};
const firebaseApp = firebase.initializeApp(config)
module.exports = {
addUser: function(req, res, db, firebase, admin) {
firebaseApp.auth().createUserWithEmailandPassword(email, password)
...
}
}