use 'readTree' to parse data file

src/components/editor.tsx

@@ -568,7 +568,7 @@ export const Editor: FC<EditorProps> = ({ onUpdate: updateState, data: editor, .
       workspace.onEditingNode({
         data: b3util.createNode(data, false),
         editable: !isSubtreeNode(data),
-        limit_error: !b3util.checkChildrenLimit(data),
+        limitError: !b3util.checkChildrenLimit(data),
       });
       setItemState(editor.selectedId, "selected", true);
     } else {

src/components/inspector.tsx

@@ -775,11 +775,21 @@ const NodeInspector: FC = () => {
           >
             <Input disabled={true} />
           </Form.Item>
-          <Form.Item name="children" label={t("node.children")}>
-            <Input
-              style={{ borderColor: editingNode.limit_error ? "red" : undefined }}
-              disabled={true}
-            />
+          <Form.Item
+            name="children"
+            label={t("node.children")}
+            rules={[
+              {
+                validator() {
+                  if (editingNode.limitError) {
+                    return Promise.reject(new Error(t("node.invalidChildren")));
+                  }
+                  return Promise.resolve();
+                },
+              },
+            ]}
+          >
+            <Input disabled={true} />
           </Form.Item>
           <Form.Item label={t("node.name")} name="name">
             <AutoComplete

src/components/register-node.ts

@@ -151,14 +151,14 @@ G6.registerNode(
         (data.path && !data.children?.length) ||
         !checkTreeData(data) ||
         (nodeDef.group && !usingGroups[nodeDef.group]) ||
-        (usingVars && data.input?.some((v) => !usingVars![v])) ||
-        (usingVars && data.output?.some((v) => !usingVars![v])) ||
         (usingVars &&
-          nodeDef.args?.some(
-            (v) =>
-              isExprType(v.type) &&
-              parseExpr(data.args?.[v.name] ?? "").some((vv) => !usingVars![vv])
-          ))
+          (data.input?.some((v) => usingVars?.[v] === undefined) ||
+            data.output?.some((v) => usingVars?.[v] === undefined) ||
+            nodeDef.args?.some(
+              (v) =>
+                isExprType(v.type) &&
+                parseExpr(data.args?.[v.name] ?? "").some((vv) => usingVars?.[vv] === undefined)
+            )))
       ) {
         classify = "Error";
         color = NODE_COLORS[classify];