[Bug Report] el-tree 控件拖拽，在火狐浏览器下拖拽报错[Vue warn]: Error in event handler for "tree-node-drag-end": "TypeError: event.dataTransfer is null" #22951
Description
Element UI version
2.15.14
OS/Browsers version
火狐浏览器
Vue version
2.7.16
Reproduction Link
Steps to reproduce
在火狐浏览器执行拖拽
What is Expected?
正常拖拽
What is actually happening?
拖拽报错