completeWith method
Completes dismissed with result if it has not already completed.
Called by the controller when a Dismiss(result: ...) action dismisses
this presented screen, so an in-flight present<T> resolves with the
action's value instead of null.
Implementation
void completeWith(Object? result) {
if (!_dismissedCompleter.isCompleted) {
_dismissedCompleter.complete(result);
}
}