From 2b92d335c22d604308d1a673cb0f6f4a652746d2 Mon Sep 17 00:00:00 2001
From: HirenGajjar <gajjarhiren111@gmail.com>
Date: Wed, 13 May 2026 02:44:51 -0700
Subject: [PATCH] fix(response): make send() a no-op when response already
 finished

Fixes #134

UwsResponse.send() threw 'Response already sent' when called on an
already-finished response. This occurred during NestJS's normal
exception-filter flow: when a handler sends a response then throws,
NestJS calls adapter.end(response) for graceful cleanup, which
delegated to send() and triggered the throw.

The throw bubbled into RouteRegistry.handleException() and was logged
as a spurious 'Unhandled route error' stack trace, even though the
client had already received their response successfully.

Changed the guard from a throw to a silent return, matching the
behavior of Express and Fastify.

Updated existing unit test in response.spec.ts to assert the new
no-op behavior (verifies end() is called exactly once, not twice).
---
 src/http/core/response.spec.ts | 5 +++--
 src/http/core/response.ts      | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/http/core/response.spec.ts b/src/http/core/response.spec.ts
index 95df507..5338ffe 100644
--- a/src/http/core/response.spec.ts
+++ b/src/http/core/response.spec.ts
@@ -536,9 +536,10 @@ describe('UwsResponse', () => {
       expect(mockUwsRes.writeHeader).toHaveBeenCalledWith('set-cookie', 'user=vikram');
     });
 
-    it('should throw if already sent', () => {
+    it('should be a no-op if already sent', () => {
       res.send('First');
-      expect(() => res.send('Second')).toThrow('Response already sent');
+      expect(() => res.send('Second')).not.toThrow();
+      expect(mockUwsRes.end).toHaveBeenCalledTimes(1);
     });
 
     it('should not throw if aborted', () => {
diff --git a/src/http/core/response.ts b/src/http/core/response.ts
index 90fa644..54d50bf 100644
--- a/src/http/core/response.ts
+++ b/src/http/core/response.ts
@@ -1268,7 +1268,7 @@ export class UwsResponse extends Writable {
     }
 
     if (this.finished) {
-      throw new Error('Response already sent');
+      return;
     }
 
     if (this.sending) {