Hi, I don’t use the PWA starter, but I did have some issues myself importing firebase into Quasar when I started. I can’t say I know the best way to do this, but I currently use the following, and it works for me:
import firebase from 'firebase/app';
import "firebase/auth";
import "firebase/firestore";
import "firebase/storage";
const config = { stuff };
firebase.initializeApp(config);
const auth = firebase.auth();
const firestore = firebase.firestore();
const storage = firebase.storage();
export {firebase, auth, firestore, storage};
And, then I import the pieces I need like this:
import { firebase, auth, firestore, storage } from './firebase.js';