_ShowcaseState.recalculateRootWidgetSize null value

[nikiforosper]

On Firebase Crashlytics, there is the following error.

_ShowcaseState.recalculateRootWidgetSize.<fn>
FlutterError - Null check operator used on a null value. Error thrown .
package:showcaseview/src/showcase.dart:476

Stack Trace:

Fatal Exception: FlutterError
0  ???                            0x0 State.context + 958 (framework.dart:958)
1  ???                            0x0 _ShowcaseState.recalculateRootWidgetSize.<fn> + 476 (showcase.dart:476)
2  ???                            0x0 SchedulerBinding._invokeFrameCallback + 1386 (binding.dart:1386)
3  ???                            0x0 SchedulerBinding.handleDrawFrame + 1322 (binding.dart:1322)
4  ???                            0x0 SchedulerBinding._handleDrawFrame + 1169 (binding.dart:1169)