Interesting. Again.
This may be happening to me, too, but I didn't recognize it as a RW problem (and I'm still not convinced it is, per se), since there is no fanfare or notification when it happens. In my case, I'm just playing the game and then suddenly I'm not. No alerts, no side effects, no nothing. I assumed I just lost connection or Steam dropped me, but after your posts here I checked my logs in the Steam/steamapps/common/RisingWorld folder and found several logs just like yours. Maybe one or two a day, and I'm on RW a LOT.
Our error logs are extremely similar. Same hardware, same JRE versions and everything. Fact is, the crash seems to be deep in the bowels of the JRE itself. Not as much fun to read as the RW server logs.
I will now pay more attention to these occurrences and see if there are log reports when it happens. In my case I have noticed one particular circumstance that seems to precede these incidents at least some of the time. Namely, when I let the game go idle while I handle a phone call or whatever, and then return to it several minutes (or more) later, as soon as I touch the game window it happens. Too many like that to be imagining it.
If I can narrow down the circumstances, I might find a clue.