NoSuchMethodError: The method '*' was called on null.

[old-traveler]

flutter 1.12.13 {StatckTrace=#0 _PagePosition.getPixelsFromPage (package:flutter/src/widgets/page_view.dart:366) #1 PageController.animateToPage (package:flutter/src/widgets/page_view.dart:204) #2 _TransformerPageViewState.onChangeNotifier (package:transformer_page_view/transformer_page_view.dart:606) #3 ChangeNotifier.notifyListeners (package:flutter/src/foundation/change_notifier.dart:206) #4 IndexController.next (package:transformer_page_view/index_controller.dart:30) #5 _SwiperTimerMixin._onTimer (package:flutter_swiper/src/swiper.dart:370) #6 _rootRunUnary (dart:async/zone.dart:1134) #7 _CustomZone.runUnary (dart:async/zone.dart:1031) #8 _CustomZone.runUnaryGuarded (dart:async/zone.dart:933) #9 _CustomZone.bindUnaryCallbackGuarded. (dart:async/zone.dart:970) #10 _rootRunUnary (dart:async/zone.dart:1138) #11 _CustomZone.runUnary (dart:async/zone.dart:1031) #12 _CustomZone.bindUnaryCallback. (dart:async/zone.dart:954) #13 _Timer._runTimers (dart:isolate-patch/timer_impl.dart:384) #14 _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:418) #15 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:174) , FlutterErrorDetail=}