I finally got the chance to log into KoL normally tonight. When I tried to go to the Trendy schedule page, I got a 502 Bad Gateway error. I've reported it via the in-game bug reporting setup.
Would a 502 response cause what we're seeing here? Obviously the trendy check isn't going to work...
As mentioned in my original post, I did try a fresh build from this morning. (10684) There's also two stack traces in the file I uploaded, one from each build I tried. (Sorry if I should have separated them, but that's how KoLmafia writes them.)
Last night (after rollover) I started up KoLmafia 15.1 (10583) and logged in. The login process got to "Seeing what's still trendy today..." and stopped. I let it sit for 15-20 minutes before I killed it. Tried it again this morning with what was the current build (10684) and got the same...