It's a shame this loses one of the most useful aspects of LLM un-minifying - making sure it's actually how a person would write it. E.g. GPT-4o directly gives the exact same code (+contextual comments) with the exception of writing the for loop in the example in a natural way:
for (var index = 0; index < inputLength; index += chunkSize) {
Comparing the ASTs is useful though. Perhaps there's a way to combine the approaches - have the LLM convert, compare the ASTs, have the LLM explain the practical differences (if any) in context of the actual implementation and give it a chance to make any changes "more correct". Still not guaranteed to be perfect but significantly more "natural" resulting code.
