In case that is not clear - to be affected by that line of code you must be creating a TypeTree from a symbol. When you create a TypeTree from a symbol, you pretty much turn your fate over to the gods, because a symbol isn't enough to tell us what a type is. It is no surprise that with all the different ways of creating things, sometimes you get what you want, and doing things consistently always means having to chase down those works-by-accident situations and redoing them in a way which will hold up. My intuition is that this is one of those cases.