Null check operator used on a null value in addTrailingChild

[jonasbadstuebner]

I got the following error message:

I/flutter (20767): Null check operator used on a null value
I/flutter (20767): #0      RenderSuperSliverList._performLayoutInner.addTrailingChild (package:super_sliver_list/src/render_object.dart:793)
I/flutter (20767): #1      RenderSuperSliverList._performLayoutInner (package:super_sliver_list/src/render_object.dart:826)
I/flutter (20767): #2      ExtentManager.performLayout (package:super_sliver_list/src/extent_manager.dart:97)
I/flutter (20767): #3      RenderSuperSliverList.performLayout (package:super_sliver_list/src/render_object.dart:448)
I/flutter (20767): #4      RenderObject.layout (package:flutter/src/rendering/object.dart:2608)
I/flutter (20767): #5      RenderSuperSliverList.layout (package:super_sliver_list/src/render_object.dart:453)
I/flutter (20767): #6      RenderSliverStickyHeader.performLayout (package:easy_chatview/src/ui/widgets/sticky_header/sliver_sticky_header_widget.dart:255)
I/flutter (20767): #7      RenderObject.layout (package:flutter/src/rendering/object.dart:2608)
I/flutter (20767): #8      RenderViewportBase.layoutChildSequence (package:flutter/src/rendering/viewport.dart:601)
I/flutter (20767): #9      RenderViewport._attemptLayout (package:flutter/src/rendering/viewport.dart:1516)
I/flutter (20767): #10     RenderViewport.performLayout (package:flutter/src/rendering/viewport.dart:1427)
I/flutter (20767): #11     RenderObject._layoutWithoutResize (package:flutter/src/rendering/object.dart:2446)
I/flutter (20767): #12     PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:1052)
I/flutter (20767): #13     PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:1065)
I/flutter (20767): #14     RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:602)
I/flutter (20767): #15     WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:1164)
I/flutter (20767): #16     RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:468)
I/flutter (20767): #17     SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1397)
I/flutter (20767): #18     SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1318)
I/flutter (20767): #19     SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:1176)
I/flutter (20767): #20     _invoke (dart:ui/hooks.dart:312)
I/flutter (20767): #21     PlatformDispatcher._drawFrame (dart:ui/platform_dispatcher.dart:419)
I/flutter (20767): #22     _drawFrame (dart:ui/hooks.dart:283

I was activating the performance overlay in the debug options, when my app crashed - I don't think this should have happened?