fix(gost): filter expected net.ErrClosed noise in service handler

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

go-gost/x/service/service.go

@@ -54,10 +54,10 @@ var needWrap = false
 
 // SetProtocolBlock sets protocol blocking switches and recomputes wrapper need
 func SetProtocolBlock(httpOn int, tlsOn int, socksOn int) {
-    isHttp = httpOn
-    isTls = tlsOn
-    isSocks = socksOn
-    needWrap = isTls+isSocks+isHttp > 0
+	isHttp = httpOn
+	isTls = tlsOn
+	isSocks = socksOn
+	needWrap = isTls+isSocks+isHttp > 0
 }
 
 type Option func(opts *options)
@@ -292,7 +292,9 @@ func (s *defaultService) Serve() error {
 			}
 
 			if err := s.handler.Handle(ctx, conn); err != nil {
-				log.Error(err)
+				if !errors.Is(err, net.ErrClosed) {
+					log.Error(err)
+				}
 				if v := xmetrics.GetCounter(xmetrics.MetricServiceHandlerErrorsCounter,
 					metrics.Labels{"service": s.name, "client": clientIP}); v != nil {
 					v.Inc()
@@ -403,12 +405,12 @@ func (s *defaultService) observeStats(ctx context.Context) {
 						TotalErrs:    st.Get(stats.KindTotalErrs),
 					},
 				}
-				
+
 				// 将流量累积到全局管理器，而不是立即上报
 				if outputBytes > 0 || inputBytes > 0 {
 					globalManager := GetGlobalTrafficManager()
 					globalManager.AddTraffic(s.name, int64(outputBytes), int64(inputBytes))
-					
+
 					// 立即重置流量计数（因为已经记录到全局管理器中）
 					if xstats, ok := st.(*xstats.Stats); ok {
 						xstats.ResetTraffic(st.Get(stats.KindInputBytes)-inputBytes, st.Get(stats.KindOutputBytes)-outputBytes)