devtrackers.gg
We usually only log a few MB/hr and it clears it every time you boot the game.
I'm guessing your 18hrs AFK probably triggered some power state that made the graphics driver stop responding -- usually we generate a lot of swearing in the log when we can't talk to the hardware any more.
Zip it up and send it to support next time (or DM it to me on discord https://discord.gg/ZdJdgM7 [DE]Glen). If it isn't a device problem it's probably an easy fix.
But otherwise... do you really want us to be optimizing for the 18hrs AFK 'in some weird state' case? I can think of a dozen issues on my list that would benefit people actually playing the game and I expect most people would rather I work on those instead.