I spent weeks trying to get GPT4 to get me through some gnarly Shapeless (Scala) issues. After that failure, I realized how real the limitations are. They really cannot produce original work and as far as niche languages, hallucinates all the time to the point of being completely unusable.
Hallucination from software generation AI is worse than software written by a beginning programmer, because at least they can analyse and determine the truth of their mistakes.