From c73cc39c61ac32fde6af1e0ac40d30a5d596eca8 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 4c86bd791..89cbf70ab 100644
--- a/server/src/index.ts
+++ b/server/src/index.ts
@@ -674,22 +674,28 @@ 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
@@ -724,17 +730,21 @@ 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
+            });
         }
       });