Syntax error. Started getting an error when we started creating multiple components.

app.jsx:39 Uncaught TypeError: Cannot read property 'string' of undefined
    at eval (eval at transform.run (babel-browser.min.js:4), <anonymous>:65:24)
    at Function.transform.run (babel-browser.min.js:4)
    at exec (babel-browser.min.js:4)
    at babel-browser.min.js:4
    at XMLHttpRequest.xhr.onreadystatechange (babel-browser.min.js:4)

function Header(props){
  return (
      <div className="header">
          <h1>{props.title}</h1>
        </div> 
  );
}

Header.propTypes = {
  title: React.PropTypes.string.isRequired,
  };

/*
function Counter(props){
  return(

  );
}
*/
function Player(props){
  return(
      <div className="player">
              <div className="player-name"> 
                  {props.name}
              </div>
                  <div className="player-score">
                      <div className="counter">
                          <button className="counter-action decrement"> - </button>
                           <div className="counter-score"> {props.score} </div>
                          <button className="counter-action increment"> + </button>
                      </div>
              </div>
      </div>
  );
}

Player.propTypes = {
  name: React.propTypes.string.isRequired, 
  score: React.propTypes.number.isRequired,
};

function Application(props) {
  return (
    <div className="scoreboard">
        <Header title={props.title} />
        <Player name="Jime Hoskins" score={31} />
    </div>
  );
}
Application.propTypes = {
  title: React.PropTypes.string,

};
Application.defaultProps = {
  title: "Scoreboard", 
}


ReactDOM.render(<Application />, document.getElementById('container'));