There was a case a few years ago where a geologist accidentally stepped into some lava. The nylon laces of his boots burned off almost instantly but the thick leather did not, and he had only minor burns on his foot. After that we all made sure that we only wear real leather boots out on active flows, not the lightweight part-nylon kind.
Revenge of the Sith, it ain’t. Still, I’m not swimming in it.
UPDATE: Reading around a bit on the site, it turns out if you aren’t wearing one of those metal bunny suits you can catch on fire from radiant heat, so Revenge of the Sith, it is.