You are talking about most obvious hallucinations such as inventing a non-existent API.
However, those are indeed trivial. What's not trivial is not using APIs that exist for your particular problem; using obsolete patterns; not recognising that a particular approach is a dead end; not recognising potential future problems. All those problems fall in the same bucket of not knowing what you don't know, yet having a (seemingly fine) solution, which is worse than not having a solution, because that would force you to go and figure things out yourself (presumably reading recent documentation, etc).
I recognise that some people approached programming in the same way before LLMs, copying stuff from SO and adjusting till it works without ever understanding what they're doing. I guess LLMs can be seen as a neat extension of that "learning style" (which btw is precisely what OP warns against), but it does seem somewhat dysfunctional.
However, those are indeed trivial. What's not trivial is not using APIs that exist for your particular problem; using obsolete patterns; not recognising that a particular approach is a dead end; not recognising potential future problems. All those problems fall in the same bucket of not knowing what you don't know, yet having a (seemingly fine) solution, which is worse than not having a solution, because that would force you to go and figure things out yourself (presumably reading recent documentation, etc).
I recognise that some people approached programming in the same way before LLMs, copying stuff from SO and adjusting till it works without ever understanding what they're doing. I guess LLMs can be seen as a neat extension of that "learning style" (which btw is precisely what OP warns against), but it does seem somewhat dysfunctional.