From 4895309fa71de1fc1514dfd38de30202d227a308 Mon Sep 17 00:00:00 2001
From: MumuTW <clothl47364@gmail.com>
Date: Fri, 6 Mar 2026 10:56:32 +0000
Subject: [PATCH] fix: handle SSE transport send errors in stdio stderr handler
 (#1014)

When the SSE connection is closed (e.g. client disconnects during rapid
reconnection), webAppTransport.send() rejects with "Not connected".
The stderr handler was calling send() without awaiting or catching the
returned promise, causing unhandled rejections that crash the server.

Add .catch() to both send() call sites in the stderr data handler so
that errors from a closed SSE connection are silently ignored instead
of crashing the process. Also move the cleanup logic in the
MODULE_NOT_FOUND branch into .finally() so transports are cleaned up
regardless of whether the notification send succeeded.
---
 server/src/index.ts | 60 ++++++++++++++++++++++++++-------------------
 1 file changed, 35 insertions(+), 25 deletions(-)

diff --git a/server/src/index.ts b/server/src/index.ts
index 4d1fffa29..92d8a541a 100644
--- a/server/src/index.ts
+++ b/server/src/index.ts
@@ -608,22 +608,28 @@ app.get(
         if (chunk.toString().includes("MODULE_NOT_FOUND")) {
           // Server command not found, remove transports
           const message = "Command not found, transports removed";
-          webAppTransport.send({
-            jsonrpc: "2.0",
-            method: "notifications/message",
-            params: {
-              level: "emergency",
-              logger: "proxy",
-              data: {
-                message,
+          webAppTransport
+            .send({
+              jsonrpc: "2.0",
+              method: "notifications/message",
+              params: {
+                level: "emergency",
+                logger: "proxy",
+                data: {
+                  message,
+                },
               },
-            },
-          });
-          webAppTransport.close();
-          serverTransport.close();
-          webAppTransports.delete(webAppTransport.sessionId);
-          serverTransports.delete(webAppTransport.sessionId);
-          sessionHeaderHolders.delete(webAppTransport.sessionId);
+            })
+            .catch(() => {
+              // SSE connection already closed, ignore
+            })
+            .finally(() => {
+              webAppTransport.close();
+              serverTransport.close();
+              webAppTransports.delete(webAppTransport.sessionId);
+              serverTransports.delete(webAppTransport.sessionId);
+              sessionHeaderHolders.delete(webAppTransport.sessionId);
+            });
           console.error(message);
         } else {
           // Inspect message and attempt to assign a RFC 5424 Syslog Protocol level
@@ -658,17 +664,21 @@ app.get(
           } else {
             level = "info";
           }
-          webAppTransport.send({
-            jsonrpc: "2.0",
-            method: "notifications/message",
-            params: {
-              level,
-              logger: "stdio",
-              data: {
-                message,
+          webAppTransport
+            .send({
+              jsonrpc: "2.0",
+              method: "notifications/message",
+              params: {
+                level,
+                logger: "stdio",
+                data: {
+                  message,
+                },
               },
-            },
-          });
+            })
+            .catch(() => {
+              // SSE connection already closed, ignore
+            });
         }
       });