pref(flowEditor): 优化 WaitEditor 组件中的代码

- 在检查 nodeData.component.customDef 时添加空值保护，提高代码健壮性

src/pages/flowEditor/nodeEditors/components/WaitEditor.tsx

@@ -25,7 +25,7 @@ const WaitEditor: React.FC<NodeEditorProps> = ({ nodeData, updateNodeData }) =>
   });
 
   useEffect(() => {
-    if (nodeData.component.customDef) {
+    if (nodeData?.component?.customDef) {
       const duration = JSON.parse(nodeData.component.customDef).duration;
       setDuration({
         hour: Math.floor(duration / 3600),