SSE set conn write deadline failed: feature not supported

[gaoshaozhen]

Describe the bug
A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior, if applicable:

1. The code is

server

func newHttpServer(cfg config.ServerConf) {
 server := rest.MustNewServer(cfg.RestConf, rest.WithCors())
 server.AddRoute(rest.Route{
 	Method:  http.MethodGet,
 	Path:    "/sse",
 	Handler: SSEMsgHandler,
 }, rest.WithSSE())
 logz.Info().Msgf("start http server %s:%d", cfg.RestConf.Host, cfg.RestConf.Port)
 go server.Start()
}

func SSEMsgHandler(w http.ResponseWriter, r *http.Request) {
 fmt.Fprintf(w, "data: %s\n\n", "ping")
 w.(http.Flusher).Flush()
 <-r.Context().Done()
}

client

req, _ := http.NewRequest(http.MethodGet, _sseURL, nil)
	resp, err := defaultHttpClient.Do(req)
	//resp, err := defaultHttpClient.Get(uri)
	if err != nil {
		fmt.Printf("err %v\n", err)
		return
	}
	reader := bufio.NewReader(resp.Body)
	for {
		line, err := reader.ReadString('\n')
		if err != nil {
			break
		}

		line = strings.TrimSpace(line)
		if strings.HasPrefix(line, "data:") {
			data := strings.TrimPrefix(line, "data:")
			fmt.Printf("recv: %s\n", data)
		} else if line == "" {
			continue
		}
	}

2. The error is

server output log
08-17 15:12:47.083 ERR core/logc/logs.go:64 > set conn write deadline failed: feature not supported gozero_level=error span=a38166ca176dfb8f trace=ababff7795221871f106231e509e8253
2025/08/17 15:13:17 http: superfluous response.WriteHeader call from github.com/zeromicro/go-zero/rest/internal/response.(*WithCodeResponseWriter).WriteHeader (withcoderesponsewriter.go:65)
08-17 15:13:17.084 ERR rest/handler/loghandler.go:133 > [HTTP] 503 - GET /sse - 127.0.0.1:52461 - Go-http-client/1.1 - slowcall(30001.4ms) duration=30001.4ms gozero_level=slow span=a38166ca176dfb8f trace=ababff7795221871f106231e509e8253
08-17 15:13:17.085 ERR rest/handler/loghandler.go:151 > [HTTP] 503 - GET /sse - 127.0.0.1:52461 - Go-http-client/1.1
GET /sse HTTP/1.1
Host: 127.0.0.1:8083
Accept-Encoding: gzip
User-Agent: Go-http-client/1.1

duration=30001.4ms gozero_level=error span=a38166ca176dfb8f trace=ababff7795221871f106231e509e8253

**Expected behavior**
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**Screenshots**
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**Environments (please complete the following information):**
- OS: [e.g. MAC]
- go-zero version [e.g. 1.9.0]

**More description**
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[kevwan]

I cannot reproduce the problem. Would you please give the complete code and steps to reproduce it?