I can't figure out how to setup [HMR]

Question

I am confused as to why my react.js code will not accept a fetch data to "https://hacker-news.firebaseio.com/v0/item/29042728.json?print=pretty". I keep getting the error "[HMR] Waiting for update signal from WDS"

My Component Code

//import './App.css';
class App extends React.Component {

    // Constructor
    constructor(props) {
        super(props);

        this.state = {
            items: [],
            DataisLoaded: false
        };
    }

    // ComponentDidMount is used to
    // execute the code
    componentDidMount() {
        fetch(
//if https://jsonplaceholder.typicode.com/users is used, then works
"https://hacker-news.firebaseio.com/v0/item/29042728.json?print=pretty")
            .then((res) => res.json())
            .then((json) => {
                this.setState({
                    isLoaded:true,
                    items: json,
                    
                });
            })
    }
    render() {
        const { DataisLoaded, items } = this.state;
        if (!DataisLoaded) return <div>
            <h1> Pleses wait some time.... </h1> </div> ;

        return (
        <div className = "App">
            <h1> Fetch data from an api in react </h1> {
                items.map((item) => (
                <ol key = { item.id } >
                    User_Name: { item.username },
                    Full_Name: { item.name },
                    User_Email: { item.email }
                    </ol>
                ))
            }
        </div>
    );
}
}

export default App;
``

I tried to fix it by going to node_modules -> webpack -> hot folder, and editing the log.js file but it's still happening.

Thank you!