[bug] 嵌套拖拽报错 #292

Describe the bug

1. 当前像官方的SortableJS 给的嵌套拖拽示例的时候，之间报错了

期望： 1. 希望官方给出一个嵌套拖拽的示例
2. react-sortablejs 渲染的节点希望能支持原生元素的所有属性，比如dataSet属性等

依赖版本：
"sortablejs": "^1.15.2"
"react-sortablejs": "^6.1.4",
"react": "^18.0.0",
"react-dom": "^18.0.0",

报错如下 1：跨组拖拽的
react-sortable.tsx:241 Uncaught TypeError: Cannot convert undefined or null to object
at Function.assign ()
at react-sortable.tsx:241:14
at Array.map ()
at $7fe8e3ea572bda7a$export$11bbed9ee0012c13.onAdd (react-sortable.tsx:240:63)
at Sortable. (react-sortable.tsx:211:12)
at dispatchEvent (sortable.esm.js:829:21)
at _dispatchEvent (sortable.esm.js:873:3)
at Sortable._onDrop (sortable.esm.js:1969:13)
at Sortable.handleEvent (sortable.esm.js:2052:14)

报错信息2：跨组拖拽的
react-sortable.tsx:236 Uncaught TypeError: Cannot read properties of null (reading 'props')
at $7fe8e3ea572bda7a$export$11bbed9ee0012c13.onAdd (react-sortable.tsx:236:43)
at Sortable. (react-sortable.tsx:211:12)
at dispatchEvent (sortable.esm.js:829:21)
at _dispatchEvent (sortable.esm.js:873:3)
at Sortable._onDrop (sortable.esm.js:1969:13)
at Sortable.handleEvent (sortable.esm.js:2052:14