fixup! fixup! fixup! Change default properties from null to undefined (#662)

Author: lukasbriza

src/helpers/isChildrenEmpty/isChildrenEmpty.js

@@ -1,4 +1,3 @@
 export const isChildrenEmpty = (children) => children == null
-  || children === undefined
   || children === false
   || (Array.isArray(children) && children.length === 0);