title: FirebaseErrorr: Missing or insufficient permissions happens, When trying to get snapShot
body: <p>I tried to get snapShot with React.js and Webpack, and had the error  Uncaught (in promise) FirebaseError: Missing or insufficient permissions. 
  Thank you very much in advance.</p>
  
  <p>I suspected my webpack setting is something wrong to make the async request. However, when I tried the simple async request with the same setup, there is no issue. On top of this, Getting document also works correctly. I'm totally lost what I should do next.</p>
  
  <p>//App.js</p>
  
  <pre><code>componentDidMount() {
      this.unsubscribeFromAuth = auth.onAuthStateChanged(async user =&gt; {
        this.setState({ user });
        await createUserProfDoc(user);
      });
    }
  </code></pre>
  
  <p>//FireBase code</p>
  
  <pre><code>export const firestore = firebase.firestore();
  export const createUserProfDoc = async (userAuth, additionalData) =&gt; {
    if (!userAuth) {
      return;
    }
    const userRef = firestore.doc('users/123');
    const snapShot = await userRef.get();
    console.log(snapShot);
  };
  </code></pre>