a use method of express.js called twice

Question

I had a very simple node.js project with express.js library set up for my project. I found that the middleware implemented using express().use() was called twice when I made a request to the nodejs server.

The following is the code-snap of the express library using and implementing middleware layer.

const express = require('express');
const app = express();

app.use((req, res, next) => {
  console.log('This is a middleware layer!');
  res.send('hello from express.');
});

module.exports = app;

May I know if there was any thing going wrong? Thanks a lot.

The following screen capture shows the console.log run twice.

https://i.stack.imgur.com/RIs6J.png