🐛 [Bug]: Picker第一个节点没有children导致级联失效

[a6930216745]

Which React Vant packages are impacted?

• react-vant (React Vant core)
• react-vant-icons(React Vant Icon)

What version of React Vant are you using?

3.2.7

Reproduce live demo(codesandebox or stackblitz)?

https://stackblitz.com/edit/stackblitz-starters-xmazgj

Descripition

[3lang3]

兄弟江苏省成自治市啦😄

[a6930216745]

兄弟江苏省成自治市啦😄

我这里实际用的是自定义类型树,第一个节点没有children很常见的现象