Pull request #3703: 无jia任务 先回退

Merge in VISUAL/fineui from ~IMP/fineui_fui:master to master

* commit '567d9e7894c3e673656468b0b40659d4a8d309b6':
  无jia任务 先回退

packages/fineui/src/core/4.widget.js

@@ -874,7 +874,7 @@ export class Widget extends OB {
         this._assetMounted();
         this.__destroy();
         this.fireEvent(Events.UNMOUNT);
-        this._purgeRef();
+        // this._purgeRef(); // 子组件unmount ref置为null了，父组件拿不到ref，导致报错
         this.purgeListeners();
     }