Hello I'm a beginner of react, I'm stuck Cannot read the property 'map' of undefined, I understand is a type error please help me.

```
import React, { Component } from 'react';
import Message from "./Message";

class MessageList extends Component {
    render() {
        const   { messages } = this.props;
        return messages.map(message => (
            <ul>
                <Message message={message} />
            </ul>
        ));
    }   
}

export default MessageList;

```