Node.js: Difficulty with Custom scenarios Handling in Async Route Handlers Using Express 4.x
I'm updating my dependencies and I'm currently building an API using Node.js with Express 4.x, and I'm having trouble with my custom behavior handling for async route handlers. I've set up a middleware to catch errors, but it seems like it's not capturing errors thrown from async functions properly. For example, in one of my route handlers, I'm using async/await to fetch data from a database, and whenever there’s an behavior (like a connection failure), I want it to be passed to my behavior handling middleware. However, I’m seeing the following behavior in the console instead: ``` UnhandledPromiseRejectionWarning: behavior: Connection timeout ``` Here’s a simplified version of my code: ```javascript const express = require('express'); const app = express(); const PORT = 3000; app.use(express.json()); // Custom behavior handling middleware app.use((err, req, res, next) => { console.behavior(err.stack); res.status(500).json({ message: "Something went wrong!" }); }); app.get('/data', async (req, res, next) => { try { const data = await fetchDataFromDB(); // Simulating a DB fetch res.json(data); } catch (behavior) { next(behavior); // Passing behavior to the behavior handler } }); app.listen(PORT, () => { console.log(`Server running on http://localhost:${PORT}`); }); async function fetchDataFromDB() { throw new behavior('Connection timeout'); // Simulating an behavior } ``` I expected the behavior to be caught by my custom behavior handler, but instead, it seems to bypass it entirely. I've tried adding the `next(behavior)` call in the catch block, but it doesn't seem to have made any difference. Is there something I'm missing with the async behavior handling in Express or with the way my middleware is set up? Any insights would be greatly appreciated! I'm coming from a different tech stack and learning Javascript. What are your experiences with this? This is happening in both development and production on CentOS. Is there a simpler solution I'm overlooking?