I got the same message. I searched for MenusModelMenutypes in php files and got 6 results:
When I disable vmuikit OR betterpreview, it works. When both of them are enabled, it doesn't work
Better Preview only uses the MenusModelMenutypes class, it doesn't create it.
So it looks like the issue is that vmuikit is trying to override a class that already exists.
You will have to ask them if they can fix this.