Bug 329930 Resetting a perspective while its active part is not defined in the perspective causes the perspective to not have an active part after the reset
1. Window > Show View > Console 2. Window > Reset Perspective... > OK 3. No parts are active.
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/PartServiceImpl.java
@Inject
	void setPart(@Optional @Named(IServiceConstants.ACTIVE_PART) MPart p) {
		if (activePart != p) {
			lastActivePart = activePart;
			activePart = p;
			
			if (constructed && !listeners.isEmpty()) {
				if (lastActivePart != null && lastActivePart != activePart) {
					firePartDeactivated(lastActivePart);
				}
				if (activePart != null) {
					firePartActivated(activePart);
				}
			}
		}
	}
	@PostConstruct
	void postConstruct() {
		eventBroker.subscribe(UIEvents.buildTopic(UIEvents.ElementContainer.TOPIC,
				UIEvents.ElementContainer.SELECTEDELEMENT), selectedHandler);
		constructed = true;
		partActivationHistory = new PartActivationHistory(this, modelService);
		if (activePart != null) {
			partActivationHistory.prepend(activePart);
		}
	}
	@PreDestroy
	void preDestroy() {
		constructed = false;
		eventBroker.unsubscribe(selectedHandler);