Whenever a sentry is satisfied that is used as an exit criterion of a task, it may occur that the containing stage completes as well. In this case, the stage's variables are removed. In some cases however, we perform another check after that whether some sentries contained in that stage are satisfied. In this case, ifPart expressions may not resolve since the stage's local variables are already gone.
Should be fixed in CmmnExecution#handleChildTransition and should not perform the second sentry check if the stage is already completed.