fix bug and add log

pkg/ruleEngine/nodes/script_filter_node.go

@@ -13,6 +13,8 @@ import (
 const jsWrapperPrifixTemplate = `function %s(msgStr, metaDataStr, msgType) { 
 									var msg = JSON.parse(msgStr);
 									var metaData = JSON.parse(metaDataStr);
+									if(!metaData === undefined)
+										metaData = {}
 									return %s(msg, metaData, msgType);
 									function %s(%s, %s, %s) {`
 const jsWrapperSuffix = `}}`
@@ -51,6 +53,7 @@ func (j *FilterJavascriptNode) OnMessage(ctx ruleEngine.Context, message *protoc
 		ctx.TellError(next, err)
 		return errors.New("metadata marshal error " + err.Error())
 	}
+	fmt.Printf("metaData-------%s:", string(metaData))
 	res, err := j.vm.Call("filter", nil, body, string(metaData), message.Type)
 	if err != nil {
 		next := j.processError(ctx, message, err)