ReactJS Firebase未捕获(在promise中) TypeError:无法读取未定义的属性“”setState“”

import React, { Component } from 'react';
import firebase from 'firebase';

class MyComponent extends Component {
  constructor(props) {
    super(props);
    this.state = {
      data: null,
      error: null,
    };
  }

  componentDidMount() {
    // 在组件挂载后，获取Firebase数据
    firebase
      .database()
      .ref('/path/to/data')
      .once('value')
      .then(snapshot => {
        // 更新组件状态
        this.setState({ data: snapshot.val() });
      })
      .catch(error => {
        // 处理错误
        this.setState({ error: error.message });
      });
  }

  render() {
    const { data, error } = this.state;

    if (error) {
      return <div>Error: {error}</div>;
    }

    if (data === null) {
      return <div>Loading...</div>;
    }

    return <div>Data: {data}</div>;
  }
}

export default MyComponent;