Retrieve data from firebase

I'm creating an application with react and I currently need to retrieve some data from database using the firebase library, so I've created a module that performs the configuration:

File: firebase.js

import firebase from 'firebase';

const config = {
    apiKey: "XYZ",
    authDomain: "XYZ.firebaseapp.com",
    databaseURL: "https://XYZ.firebaseio.com",
    projectId: "XYZ",
    storageBucket: "XYZ.appspot.com",
    messagingSenderId: "123"
};

export default firebase.initializeApp(config);

Inside another module I include the configuration module and start using it:

import React, { Component } from 'react'
import firebase from '../../firebase'

export default class MeuComponent extends Component {
    componentDidMount () {
        console.log('did mount');
        var dbRef = firebase.database().ref().child('apiDataReference');
        dbRef.on('value', snap => console.log(snap.val()));
    }
 ...
}

When the component is rendered I see the did mount used in the console.log() , however I get the following error then:

  

unreachable code after return statement Learn more