Fix printing too many warnings (#27015)

Signed-off-by: longjiquan <jiquan.long@zilliz.com>

internal/util/flowgraph/node.go

@@ -200,6 +200,11 @@ func (node *BaseNode) IsValidInMsg(in []Msg) bool {
 		return false
 	}
 
+	if len(in) == 0 {
+		// avoid printing too many logs.
+		return false
+	}
+
 	if len(in) != 1 {
 		log.Warn("Invalid operate message input", zap.Int("input length", len(in)))
 		return false