As some have already figured out, a client patch was pushed today. It's for preparation of the new animal type colors, and a few other things. Well, with this update, LiveMap was broken and some are getting a fatal error trying to launch Wurm after running the patcher.bat that you normally would run after an update...so here's how you can fix it:
1. Install the new version of LiveMap - github.com/ago1024/LiveHudMap/releases/tag/v1.7
2. Install the new version of ModLoader - github.com/ago1024/WurmClientModLauncher/releases/tag/v0.8.1
3. Run patcher.bat in your WurmLauncher folder.