Hide previous/next button when prevLabel/nextLabel is set to null (#436)
Hide previous/next button when prevLabel/nextLabel is set to null (#436)

* Fixed issue where setting prevLabel or nextLabel to null, while making the button invisible, would still render it

Co-authored-by: benomatis <9a54f2cad19740bf159162529362d1cc2b0f48b9@gmail.com>
wojtekmaj/react-calendar,wojtekmaj/react-calendar,wojtekmaj/react-calendar