use ]flutter_swiper plugins, throw this error

[zileyuan]

Launching lib/main.dart on M811 in debug mode...
Built build/app/outputs/apk/debug/app-debug.apk.
I/flutter (10707): ══╡ EXCEPTION CAUGHT BY SCHEDULER LIBRARY ╞═════════════════════════════════════════════════════════
I/flutter (10707): The following NoSuchMethodError was thrown during a scheduler callback:
I/flutter (10707): The method 'findRenderObject' was called on null.
I/flutter (10707): Receiver: null
I/flutter (10707): Tried calling: findRenderObject()
I/flutter (10707): When the exception was thrown, this was the stack:
I/flutter (10707): #0 Object.noSuchMethod (dart:core/runtime/libobject_patch.dart:50:5)
I/flutter (10707): #1 _TransformerPageViewState._onGetSize
package:transformer_page_view/transformer_page_view.dart:455
I/flutter (10707): #2 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._invokeFrameCallback
package:flutter/…/scheduler/binding.dart:988
I/flutter (10707): #3 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.handleDrawFrame
package:flutter/…/scheduler/binding.dart:936
I/flutter (10707): #4 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._handleDrawFrame
package:flutter/…/scheduler/binding.dart:840
I/flutter (10707): #8 _invoke (dart:ui/hooks.dart:209:10)
I/flutter (10707): #9 _drawFrame (dart:ui/hooks.dart:168:3)
I/flutter (10707): (elided 3 frames from package dart:async)
I/flutter (10707): ════════════════════════════════════════════════════════════════════════════════════════════════════

[zileyuan]

in function
void onGetSize() {
RenderObject renderObject = context.findRenderObject();
Size size = renderObject?.paintBounds?.size;
_calcCurrentPixels();
onGetSize(size);
}

and context is null

[cabbage217]

怎样才能看到左右两边的图片?