Functions are not valid as a Rea

Functions are not valid as a React child. This may happen if you return a Component instead of <Component /> from render. Or maybe you meant to call this function rather than return it.

如下源码导致报错
<Route path="/demo" element={Demo} />

原因：element 的值是组件 注意格式

修复如下：
<Route path="/demo" element={<Demo />} />