example in readme doesn't work

[masukomi]

the require line doesn't work as-is and once you eventually coax it into something that does work you get an app that just spits out

2018-06-09 20:11:53.365 crystal-run-app.tmp[15858:15753157] app launched

and nothing else. Judging by the code there's supposed to be a window and a button and the button should do something when clicked.