MERN stack Auth

Hey guys , I haven’t completed the free code camp curriculum yet, but I was able to come up with a login and register system with the mern stack.
Please I need you to view the code and check if they is a way I could improve in security .

My repository—> https://github.com/Joel-Ajayi/MERN_COMPLETE_AUTH

What is it specifcally you want people to look at?
Do you have a bug or don’t you? Does your code work or does is it not?

Just to check if they is a way I could improve the code