If you were attentive enough, you didn't miss that, in container's JSX, we introduced a new component ErrorAlert. Since we have an error state (state.feedError), we need to visualize it:
./app/ts/Components/ErrorAlert.tsx
import * as React from "react"; import { Dialog, DialogTitle, DialogContent, DialogActions, Button } from "react-mdl"; import { TStore } from "../Interfaces"; interface IProps { store: TStore; } export default class ErrorAlert extends React.Component<IProps, {}> { private onClose = () => { this.props.store.setFeedError( "" ); } render() { const { feedError } = this.props.store.state; return ( <Dialog open={Boolean(feedError)}> <DialogTitle>Houston, we have a problem</DialogTitle> ...