Process::HandlePrivateEvent:
sets m_currently_handling_event.SetValue(true, eBroadcastNone);
at the start and:
m_currently_handling_event.SetValue(false, eBroadcastAlways);
at the end, however the case for NextEventAction::eEventActionExit returns, that should also set it to false to avoid the deadlock when someone is calling "Halt" at the same time/later, which waits for this to be false.