I normally host a dedicated server, but with the current "Connection to Server failed not running the app", friend can't connect via dedicated. So I went to host local co-op and the game went blank, like it usually does before bringing up the GUI of the co-op server, but it actually crashed to desktop, messed up my resolution(taskbar was stuck at 1920x1080, I had to manually reset my resolution to fix it) and now refuses to open at all. I get 2 different errors in my EventViewer- I've attached the most recent logs, but I'm not sure how helpful they will be. EDIT: Verifying the Steam files discovered one file corrupt. It re-downloaded and I was able to play the game again. However, upon trying a second time to run local co-op the exact same thing happened and I had to reboot to re-download the corrupt file again. It appears to be the Empyrion.exe in the Client folder that is being replaced.
I just tested hosting a Local Co-op game and it appears to work with no crashes or immediate issues present.