You ahve to remove WhyYouNoMakeGoodMap and ItsBecauseYouNo…(forget the rest of the name) to stop that error.
This will also stop the world being void and the island spawning, so either upload a map created in single player (if just you and some friends will be playing) or use the SkyClaims plugin.
To generate the void world you might also be able to use level-type=botania-skyblock