Hey Andrew, question for you about something the article litely touches on but doesn't really discuss further:

> If the programmer uses async() where they should have used asyncConcurrent(), that is a bug. Zig's new model does not (and cannot) prevent programmers from writing incorrect code, so there are still some subtleties to keep in mind when adapting existing Zig code to use the new interface.

What class of bug occurs if the wrong function is called? Is it "UB" depending on the IO model provided, a logic issue, or something else?