wtf? you just have to provide a position object for $center. That means you have to change the type hint of $center to Position and pass an position. OP should fix the type hint..
Ok thanks, will try, so the type hint in the "tutorial" is wrong, since Vector3 doesn't support getLevel()
It is wrong. In type-strict object-oriented languages (which we are pretending to be), if your variable type is of a superclass, you can't assume it to be of a subclass. This assumption makes type hinting meaningless as you aren't using the type hint at all. You guys should really take a look at PEMapModder's WorldEditArt plugin (under https://github.com/LegendOfMCPE/WorldEditArt) for the algorithms! PEMapModder's core value of non-pragmatism made most of his work unusable for servers (not directly), but for programmers they indeed have great value!