I'm getting the following error when compiling

Compiler message:
../../../AppData/Local/Pub/Cache/hosted/pub.dartlang.org/syncfusion_flutter_sliders-18.3.40-beta/lib/src/slider.dart:1232:7: Error: The non-abstract class '_RenderSliderElement' is missing implementations for these members:
RenderObjectElement.insertChildRenderObject
RenderObjectElement.moveChildRenderObject
RenderObjectElement.removeChildRenderObject