child is uniformly converted into null.
return Children.map(children as ReactElement<any>[], (child, index) => {
if (child === undefined) return undefined;
const item = list[index] || {};
const { className: prevClassName } = child.props;
// @todo - handle the function if avalable. I don't think anyone will be doing this soon.
const filtered = typeof filter === "string" && {
[filter.replace(".", "")]: !!item.filtered,
};
childis uniformly converted into null.