I've noticed that with clojure(script) unless you specifically instruct them to keep nesting levels low, they can hit a point where they make a paren placement error and can't debug their way out of it. Although in my case while one model made the error then couldn't find what it had done, a second model that I switched to was then able to identify it and back it out. So I suspect this is a transient weakness in today's models, not something fundamental.