React js or Angular which one is more stable?

I am a software engineering student interning at a company. I just started learning react js, and would like to use it to develop a web app for the company where i am working at. However, my colleague developer think that because react is an open source library, it is subject to being updated anytime, and therefore its not very stable. I am aware that the current released react version is stable, however should I be worried that a newer version would come that will conflict with the previous one? Also, since react is not very structured and therefore has some better and bad practices would you encourage a beginner to use it for a big project?