淘宝拉数据一亿条 5小时都没没看见问题？估计是自己写法问题（promise报错未捕获）异步未捕获导致的吧

That particular error occurs whenever your code attempts to send more than one response to the same request. There are a number of different coding mistakes that can lead to this:

每当您的代码尝试向同一请求发送多个响应时，就会发生该特定错误。 有许多不同的编码错误可能导致这种情况：

1. Improperly written asynchronous code that allows multiple branches to send a response.

   编写不正确的异步代码，允许多个分支发送响应。

2. Not returning from the request handler to stop further code in the request handler from running after you've sent a response.

   在发送响应后，不从请求处理程序返回以阻止请求处理程序中的其他代码运行。

3. Calling next() when you've already sent a response.

   当您已发送响应时调用next()。

4. Improper logic branching that allows multiple code paths to execute and attempt to send a response.

   不正确的逻辑分支允许多个代码路径执行并尝试发送响应。

   ---

   // Testing for async errors using Promise.catch.
   it('tests error with promises', () => {
     expect.assertions(1);
     return user.getUserName(2).catch(e =>
       expect(e).toEqual({
         error: 'User with 2 not found.',
       }),
     );
   });
   
   // Or using async/await.
   it('tests error with async/await', async () => {
     expect.assertions(1);
     try {
       await user.getUserName(1);
     } catch (e) {
       expect(e).toEqual({
         error: 'User with 1 not found.',
       });
     }
   });