In this repo I continue practicing React concepts learned while following this great course https://www.udemy.com/course/react-the-complete-guide-incl-redux/. The code lets you add a user (username and age) and render it inside a list (React Refs are used to "grab" the form input instead of useState). When adding the user to the list, the content is validated by checking that no field is left empty and the age is not <0. In case of error, a Modal component is shown and this can be closed either by clicking on the close button or outside the modal.