Validator: Detect error for synchronization with events in eventdriven execution

[f4l0]

In the event-driven execution, it is not possible to synchronize purely event based.Therefore, the validator should throw an error. In the cycle-based case, it is possible, but still very unlikely that both events fire at the same time. Thus I think, the validator should give a warning.

To archive such a behavior today you must use dummy success nodes: