Express: handle pipe errors gracefully (#5052)

* handle pipe errors gracefully

* move handlers at the top

Author: ruggi

utopia-remix/server.js

@@ -8,6 +8,15 @@ import * as path from 'node:path'
 import * as url from 'node:url'
 import sourceMapSupport from 'source-map-support'
 
+// To make sure everything keeps working and the server doesn't crash, if
+// there are any uncaught errors, log them out gracefully
+process.on('uncaughtException', (err) => {
+  console.error('server uncaught exception', err)
+})
+process.on('unhandledRejection', (err) => {
+  console.error('server unhandled rejection', err)
+})
+
 // figlet -f isometric3 'utopia'
 const asciiBanner = `
       ___                       ___           ___                     ___
@@ -143,7 +152,14 @@ function proxy(originalRequest, originalResponse) {
     },
   )
 
-  originalRequest.pipe(proxyRequest)
+  originalRequest
+    .pipe(proxyRequest)
+    // if the request fails for any non-explicit reason (e.g. ERRCONNREFUSED),
+    // handle the error gracefully and return a common status code back to the client
+    .on('error', (err) => {
+      console.error('failed proxy request', err)
+      originalResponse.status(502).json({ error: 'Service temporarily unavailable' })
+    })
 }
 
 const corsMiddleware = cors({