[bug] avoid empty inbound

Co-Authored-By: Alireza Ahmadi <alireza7@gmail.com>

web/service/inbound.go

@@ -317,7 +317,6 @@ func (s *InboundService) UpdateInbound(inbound *model.Inbound) (*model.Inbound,
 		oldInbound.Tag = fmt.Sprintf("inbound-%v:%v", inbound.Listen, inbound.Port)
 	}
 
-
 	needRestart := false
 	s.xrayApi.Init(p.GetAPIPort())
 	if s.xrayApi.DelInbound(tag) == nil {
@@ -509,6 +508,10 @@ func (s *InboundService) DelInboundClient(inboundId int, clientId string) (bool,
 		}
 	}
 
+	if len(newClients) == 0 {
+		return false, common.NewError("no client remained in Inbound")
+	}
+
 	settings["clients"] = newClients
 	newSettings, err := json.MarshalIndent(settings, "", "  ")
 	if err != nil {