First, I see you’re essentially retrieving the whole result list and storing everything in the same list. Scrolling won’t help you much here: it’s supposed to help you process data in chunks, releasing memory after each chunk, which you’re obviously not doing here.
I’d suggest using .fetchAllHits() instead of scroll() if your intent really is to fetch the whole result list. Whatever approach you choose, be warned that you may hit an OutOfMemoryError if your dataset is too large.
Now about the exception… it definitely looks like a bug. I’m investigating and will update you.