fix(mindmap): 补全 ensureActiveBefore 防止工具栏报错

wolai-frontend/src/components/editor/blocks/MindmapBlock.tsx

@@ -82,6 +82,26 @@ const applyToActiveNodes = (
   (mindmap.renderer?.activeNodeList ?? []).forEach(handler);
 };
 
+// 确保存在激活节点后再执行命令，若无则自动选中根节点
+const ensureActiveBefore = (mindmap?: MindMapInstance | null) => {
+  const mm = mindmap ?? null;
+  if (!mm) {
+    window.alert("思维导图尚未初始化");
+    return null;
+  }
+  const list = mm.renderer?.activeNodeList ?? [];
+  if (!list || list.length === 0) {
+    const root = mm.renderer?.root ?? mm.renderer?.renderTree?._node;
+    if (root) {
+      mm.execCommand?.("SET_NODE_ACTIVE", root, true);
+    } else {
+      window.alert("请先选中一个节点");
+      return null;
+    }
+  }
+  return mm;
+};
+
 const MindmapBlockView = ({
   block,
   editor,