[keybored]

I love libraries that does a simple check and signals that it "failed" with ThingWasNotTrueException.

In surprising twist: Java has ConcurrentModificationException. And, to counter its own culture of exception misuse, the docs have a stern reminder that this exception is supposed to be thrown when there are bugs. You are not supposed to use it to, I dunno, iterate over the collection and bail out (control flow) based on getting this exception.