JavaScript React Basics (retired) Designing Data Flow Restructuring State

propTypes

propTypes: { title: PropTypes.string, initialPlayers: PropTypes.arrayOf(PropTypes.shape({ name: PropTypes.string.isRequired, score: PropTypes.num.isRequired, id: PropTypes.num.isRequired, })).isRequired, }

Hello, I am working with this piece of data, however I am using create-react-app and I cannot get my app to load due to the "arrayOf(PropTypes" it's throwing an error between the "f" and the "(", as if it does not like the arrayOf shape combo. Can you please guide me as to what could be the issue?