App.jsx

// ...

export class App extends React.Component
{
    static propTypes = {
        auth: PropTypes.object.isRequired
    };

    render() {
        // ...
        return (
            <div id="app">
                <Header />
                
                <Route exact path="/" component={MainPage} />
                <Route path="/stores" component={StoresPage} />
                <Route path="/products" component={ProductsPage} />
                <Route path="/products/:slug" component={ProductDetailPage} />
                
                <Footer />
            </div>
        );
    }
}

index.jsx

//...

render(
    <Provider store={store}>
        <BrowserRouter>
            <Switch>
                <App />
                <Route component={NotFound} />
            </Switch>
        </BrowserRouter>
    </Provider>,
    document.getElementById('app')
);