better logs

src/proxy.js

@@ -447,5 +447,16 @@ export function createProxyApp({ keys, keyRotator = createKeyRotator(keys), fetc
     }
   });
 
+  // `express.json()` reports a client that closes its upload stream as a
+  // `request.aborted` error. At that point there is no client left to send a
+  // response to, so prevent Express's default error handler from printing a
+  // misleading stack trace for an expected disconnect.
+  app.use((error, request, response, next) => {
+    if (error?.type !== 'request.aborted') return next(error);
+
+    response.statusCode = 499; // Conventional internal status for client-closed requests.
+    console.warn(`Client disconnected while uploading request body: ${request.method} ${request.originalUrl} from ${clientIp(request)}`);
+  });
+
   return app;
 }