Fix: Fixed the issue where the operator added by clicking the plus sign in the data flow would overlap with the original section #9886 (#10458)

### What problem does this PR solve?

Fix: Fixed the issue where the operator added by clicking the plus sign
in the data flow would overlap with the original section #9886

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

web/src/pages/agent/hooks/use-add-node.ts

@@ -116,6 +116,7 @@ export const useInitializeOperatorParams = () => {
       [Operator.UserFillUp]: initialUserFillUpValues,
       [Operator.StringTransform]: initialStringTransformValues,
       [Operator.TavilyExtract]: initialTavilyExtractValues,
+      [Operator.Placeholder]: {},
     };
   }, [llmId]);