Right now the archiver always says, "We succeeded on howevermany threads!", even if it also failed on some. This is misleading; it should call out that some failed. I only noticed it had due to noticing an aberration on a single-page test, which had a roughly 2% chance of happening, so that's not great.

Successfully downloaded 57 threads, failed to download 2 threads, see log for details <-- or something like that would be sufficient to know that things blew up