Hi there. I’ve been stuck for the past week and a half, despite uninstalling and reinstalling. Today, I decided to do a full thorough sweep, and found a dedicated folder in C:\Users<user>\AppData\Local. I deleted it and installed the game again, and I was able to start a new game without fatal error. Hope this helps!
Pro tip: as the game is in development, I would avoid getting too attached to any save file as they may get corrupted or unrecognized in newer versions.