fix: 修复对象添加到组中出现问题

src/component/Canvas/CanvasEditor/commands/ObjectLayerCommands.js

@@ -229,7 +229,7 @@ export class AddObjectToLayerCommand extends Command {
             evented: true, // 设置对象可事件
           });
           // 如果对象父图层有 裁剪  则更新裁剪
-          if (parent.clippingMask) {
+          if (parent?.clippingMask) {
             const clippingMaskFabricObject = await restoreFabricObject(
               parent.clippingMask,
               this.canvas