fix key scan err handling

task3-backend/lib/server.go

@@ -165,19 +165,17 @@ func (s *Server) readKey(conn net.Conn) (key string, err error) {
 
 	scanner.Buffer(buf, 0)
 
-	for {
+	ok := scanner.Scan()
 	err = scanner.Err()
+
 	if err != nil {
-			return
+		log.Debugf("cannot scan, %v", err)
 	}
-
+	if !ok {
-		if !scanner.Scan() {
+		return
-			continue
 	}
 
 	key = scanner.Text()
-		break
-	}
 
 	return
 }