Bug 299272 Renderer cannot handle an MPart with a null label
java.lang.IllegalArgumentException: Argument cannot be null at org.eclipse.swt.SWT.error(SWT.java:4049) at org.eclipse.swt.SWT.error(SWT.java:3983) at org.eclipse.swt.SWT.error(SWT.java:3954) at org.eclipse.e4.ui.widgets.CTabItem.setText(CTabItem.java:1013) at org.eclipse.e4.workbench.ui.renderers.swt.StackRenderer.showChild(StackRenderer.java:296) at org.eclipse.e4.workbench.ui.renderers.swt.LazyStackRenderer.processContents(LazyStackRenderer.java:92) at org.eclipse.e4.ui.workbench.swt.internal.PartRenderingEngine.createGui(PartRenderingEngine.java:300) at org.eclipse.e4.ui.workbench.swt.internal.PartRenderingEngine.createGui(PartRenderingEngine.java:349) at org.eclipse.e4.workbench.ui.renderers.swt.SWTPartRenderer.processContents(SWTPartRenderer.java:54) at org.eclipse.e4.ui.workbench.swt.internal.PartRenderingEngine.createGui(PartRenderingEngine.java:300) at org.eclipse.e4.ui.workbench.swt.internal.PartRenderingEngine.createGui(PartRenderingEngine.java:349) at org.eclipse.e4.workbench.ui.renderers.swt.SWTPartRenderer.processContents(SWTPartRenderer.java:54) at org.eclipse.e4.workbench.ui.renderers.swt.WBWRenderer.processContents(WBWRenderer.java:369) at org.eclipse.e4.ui.workbench.swt.internal.PartRenderingEngine.createGui(PartRenderingEngine.java:300) at org.eclipse.e4.ui.workbench.swt.internal.PartRenderingEngine.createGui(PartRenderingEngine.java:349) at org.eclipse.e4.ui.workbench.swt.internal.PartRenderingEngine$4.run(PartRenderingEngine.java:510)
bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/workbench/ui/renderers/swt/StackRenderer.java
public StackRenderer() {
		super();
	}
	@PostConstruct
	public void init(IEventBroker eventBroker) {
		super.init(eventBroker);
		EventHandler itemUpdater = new EventHandler() {
			public void handleEvent(Event event) {
				Object objElement = event
						.getProperty(UIEvents.EventTags.ELEMENT);
				
				if (!(objElement instanceof MUILabel)
						|| !(objElement instanceof MUIElement))
					return;
				
				MUIElement uiElement = (MUIElement) objElement;
				MUILabel modelItem = (MUILabel) objElement;
				
				MElementContainer<MUIElement> parent = uiElement.getParent();
				if (!(parent.getRenderer() == StackRenderer.this))
					return;
				
				MElementContainer<MUIElement> stack = uiElement.getParent();
				CTabItem item = findItemForPart(stack, uiElement);
				if (item == null)
					return;
				String attName = (String) event
						.getProperty(UIEvents.EventTags.ATTNAME);
				if (UIEvents.UILabel.LABEL.equals(attName)) {
					String newName = (String) event