Broken in Flutter 3.0.0

[ultimate-tester]

As of Flutter 3.0.0, the SplashScreen is completely broken. It crashes with the exception and trace:

======== Exception caught by scheduler library =====================================================
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      SplashScreen.build.<anonymous closure> (package:rive_splash_screen/rive_splash_screen.dart:130:18)
#1      _RiveLoadingState._finished.<anonymous closure> (package:rive_loading/rive_loading.dart:134:25)
#2      SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1146:15)
#3      SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1091:9)
#4      SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:997:5)

From user perspective a fix is to assign the onError function, then it will work without issues.