"Null check operator used on a null value" was thrown during a scheduler callback

[willbryant]

Getting this sometimes, I think when I have scrolled the container that contains the slide into view and then scroll it out, but I can't reproduce it consistently.

The following _CastError was thrown during a scheduler callback:
Null check operator used on a null value

When the exception was thrown, this was the stack: 
#0      SlideActionState.initState.<anonymous closure> (package:slide_to_act/slide_to_act.dart:387:39)
#1      SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1144:15)
#2      SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1090:9)
#3      SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:998:5)
#7      _invoke (dart:ui/hooks.dart:161:10)

Which comes from:

      final RenderBox containerBox =
          _containerKey.currentContext!.findRenderObject() as RenderBox;

[ambogatyrev]

I have some issue((
were you able to fix it?

[willbryant]

I think we're using https://pub.dev/packages/slide_to_confirm at the moment.