I noticed that when cloning an
InstancedMesh, the method description says that the second argument is
newParent (optional Node), which is how it works for
Mesh too. In the definition of the method in TypeScript however,
newParent is not optional, so TS is complaining when cloning instances without setting a parent.
In the implementation of the method it is checked if
newParent exists so it is indeed optional, just the type in the method definition is wrong.