And another one idea, also about Anko.
What about properties, which only can be set?
In Android, you can set a Drawable, a resource ID, a Uri, an Icon, or a Bitmap into an ImageView, and a Drawable will be set internally, thus it has only getDrawable getter.
Anko has extension properties for many of these cases, but throws exceptions in getters, deferring a logical failure into runtime.
/* There's also a better way: @Deprecated getter with ERROR level. */