From 1b34889b7dd4bd0ee4f6997acf38f6072f2fde98 Mon Sep 17 00:00:00 2001
From: Weixie Cui <cuiweixie@gmail.com>
Date: Fri, 20 Feb 2026 18:54:59 +0800
Subject: [PATCH] fix: if return false shoulde set to value

Signed-off-by: Weixie Cui <cuiweixie@gmail.com>
---
 lib/response.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/response.js b/lib/response.js
index f965e539dd2..bc2bc6fb438 100644
--- a/lib/response.js
+++ b/lib/response.js
@@ -673,7 +673,7 @@ res.header = function header(field, val) {
       if (Array.isArray(value)) {
         throw new TypeError('Content-Type cannot be set to an Array');
       }
-      value = mime.contentType(value)
+      value = mime.contentType(value) || value
     }
 
     this.setHeader(field, value);