Nodejs - Angular，正在向nodejs发送请求我收到此错误

// Node.js后端代码示例
const express = require('express');
const cors = require('cors');
const app = express();

app.use(cors());

app.get('/data', (req, res) => {
  res.json({ message: 'Hello from Node.js!' });
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

// Angular前端代码示例
import { HttpClient } from '@angular/common/http';
import { Injectable } from '@angular/core';

@Injectable({
  providedIn: 'root'
})
export class DataService {
  private apiUrl = 'http://localhost:3000/data';

  constructor(private http: HttpClient) {}

  getData() {
    return this.http.get(this.apiUrl);
  }
}

// Angular前端代码示例
import { HttpClient, HttpHeaders } from '@angular/common/http';
import { Injectable } from '@angular/core';

@Injectable({
  providedIn: 'root'
})
export class DataService {
  private apiUrl = 'http://localhost:3000/data';
  private headers = new HttpHeaders({
    'Authorization': 'Bearer your-token'
  });

  constructor(private http: HttpClient) {}

  getData() {
    return this.http.get(this.apiUrl, { headers: this.headers });
  }
}

# 启动Node.js服务器
node server.js