DOM中未显示react codemirror2

如何解决DOM中未显示react codemirror2

enter image description here

我已经尝试过在此页面上找到的内容：react-codemirror2 has no CSS effect

但是我只得到图片中显示的内容，有人可以帮我吗？

import React,{ Component } from "react";

// Import the code mirror component.
import { Controlled } from "react-codemirror2";

// The following two imports is for the theme.
import 'codemirror/lib/codemirror.css';
import 'codemirror/theme/material.css';

// This import is for the language Syntax highlighting.
import 'codemirror/mode/javascript/javascript.js';

export default class App extends Component {
  constructor(props) {
    super(props);
    this.state = {
       src: ''
    }
  }

  render() {
    let option = {
      mode: 'javascript',theme: 'material'
    };

    return (
      <div>
        <Controlled
          value={this.state.src}
          option={option}
          onBeforeChange={(editor,data,value) => {
            this.setState({ src: value });
          }}
          onChange={(editor,value) => {}}
        />
      </div>
    )
  }
}