Results 2 issues of Joel Christophel

`` The above code produces: ![image](https://user-images.githubusercontent.com/5117047/55753631-d32a7200-5a18-11e9-9a97-80ac6b470323.png) The role of a native checkbox is implicity `checkbox`. Further, the code is interpreted as `checked=""`, which is invalid.

better-error-warning-message