RangeError (length): Invalid value: Only valid value is 0: 1

[apaolino]

Hi, thanks for this library.
I'm getting this error highlighted in Crashlytics (Android 7.1.1, Tutorial v1.0.8)

Non-fatal Exception: io.flutter.plugins.firebase.crashlytics.FlutterError: RangeError (length): Invalid value: Only valid value is 0: 1. Error thrown Instance of 'ErrorDescription'.
       at Tutorial.showTutorial.<fn>.<fn>.<fn>(tutorial_tutorial.dart)
       at GestureRecognizer.invokeCallback(recognizer.dart:198)
       at TapGestureRecognizer.handleTapUp(tap.dart:608)
       at BaseTapGestureRecognizer._checkUp(tap.dart:296)
       at BaseTapGestureRecognizer.handlePrimaryPointer(tap.dart:230)
       at PrimaryPointerGestureRecognizer.handleEvent(recognizer.dart:563)
       at PointerRouter._dispatch(pointer_router.dart:94)
       at PointerRouter._dispatchEventToRoutes.<fn>(pointer_router.dart:139)
       at _LinkedHashMapMixin.forEach(_LinkedHashMapMixin.java)
       at PointerRouter._dispatchEventToRoutes(pointer_router.dart:137)
       at PointerRouter.route(pointer_router.dart:123)
       at GestureBinding.handleEvent(binding.dart:439)
       at GestureBinding.dispatchEvent(binding.dart:419)
       at RendererBinding.dispatchEvent(binding.dart:322)
       at GestureBinding._handlePointerEventImmediately(binding.dart:374)
       at GestureBinding.handlePointerEvent(binding.dart:338)
       at GestureBinding._flushPointerEventQueue(binding.dart:296)
       at GestureBinding._handlePointerDataPacket(binding.dart:279)