OK, wow - that example kind of perfectly proves my point. If I were to ask ChatGPT an extremely specific, low-level question about an extremely niche topic, then I would absolutely be on "high alert" that it wouldn't know the answer. And while I agree the "confidence" with which ChatGPT asserts its answers (though I'd argue the GPT-4 version does a much better job at not being over-confident than 3.5) is off-putting, I think it's pretty easy to detect where it's wrong.
I'd also be curious about your Java example. There was a good YouTube video of a guy that got ChatGPT to write a "population" game for him. In some cases on first try it would output code that had compile errors, e.g. because it had wrong versions of Python dependencies. He would just paste the errors back in to ChatGPT and ChatGPT would correct itself. Again, though, this highlights my point that I use ChatGPT as the start of my processes, a 1st draft if you will. I don't just ask it to write some code, then when I get an error throw my hands up and say "see how dumb ChatGPT is." To each their own, though.
I don't consider a popular video game from 2009 to be "extremely niche", and I also shouldn't have to know what ChatGPT knows. And no, I don't think it's easy to detect where it's wrong if you don't know the right answer, and it's actually pretty useless when you have to spend time confirming answers.
I was also using it to generate some Java code for a bit. That is, until it started giving me maven dependencies that didn't exist, and classes that didn't exist, but definitely looked like they would at first glance.