Examples should not retry on bad randomness keys in a loop

[real-or-random]

Well, we should change the other examples and perhaps also the API docs. Creating keys in a while loop is not good practice. If you hit an invalid key, you're most probably not very lucky, but very unlucky because your randomness is broken. But hey, yeah, let's just yolo and try again. :)

Originally posted by @real-or-random in #1519 (comment)

[real-or-random]

Resolved by #1570 and #1616.