I can't get anything to work in it. Just for fun I put the not minifed vue.js source inside and I get: null or undefined TypeError at repl:537:23 at repl:5:1

I can't get anything to work in it. Just for fun I put the not minifed vue.js source inside and I get: null or undefined TypeError at repl:537:23 at repl:5:16 at repl:2:2