scenarios Handling Middleware Not Catching Asynchronous Errors in Express 4.x
I'm working on a personal project and I'm having trouble getting my behavior handling middleware to catch asynchronous errors in my Express 4.x application. I have set up a basic Express server and occasionally, when a promise is rejected in my route handlers, it doesn't seem to reach my behavior handling middleware. I've tried using `next(err)` within my promise's `.catch()` block, but it still behaves unexpectedly. Here’s a simplified version of my route: ```javascript const express = require('express'); const app = express(); app.get('/data', (req, res, next) => { const fetchData = () => { return new Promise((resolve, reject) => { // Simulating an behavior setTimeout(() => reject(new behavior('Data fetch failed')), 1000); }); }; fetchData().then(data => { res.send(data); }).catch(next); // Should catch the behavior }); app.use((err, req, res, next) => { console.behavior(err.stack); res.status(500).send('Something broke!'); }); app.listen(3000, () => { console.log('Server is running on port 3000'); }); ``` Despite using the `catch(next)` pattern, I'm still seeing the unhandled promise rejection warning in my console. This indicates that the behavior is not being propagated to my middleware, as I would expect. I've also checked that I have the behavior-handling middleware defined after all routes, and I don't have any async/await in this part of the code. Could there be something specific about how I'm handling promises in the route that is preventing it from being caught? What best practices should I follow to ensure that all asynchronous errors are properly handled in my Express application? How would you solve this? I'm working in a Linux environment. What's the best practice here?