index.js da raiz da aplicação, configurado para receber a store do mobx

index.js

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import * as serviceWorker from './serviceWorker';

import { Provider } from 'mobx-react';
import RootStore from '../src/mobx/RootStore';

const Root = (
    <Provider RootStore={RootStore}>
        <App />
    </Provider>
)

ReactDOM.render(Root, document.getElementById('root'));

// If you want your app to work offline and load faster, you can change
// unregister() to register() below. Note this comes with some pitfalls.
// Learn more about service workers: https://bit.ly/CRA-PWA
serviceWorker.unregister();