Hullo! I have a bug for the MZ Demo Project, but I can't access the console log. When I beat the floor 1 boss, the game crashes.
Viewing post in Bug Report
The fix for this is pretty extensive. It's detailed out here: https://itch.io/post/11665036
Just don't load a save in the roguelike dungeon and you should be fine. This has been fixed for the next update (v1.6.3).