Bug 208791 [Markers] NPE in ExtendedMarkersView
org.eclipse.swt.SWTException: Failed to execute runnable (java.lang.NullPointerException) at org.eclipse.swt.SWT.error(SWT.java:3706) at org.eclipse.swt.SWT.error(SWT.java:3624) [... snip ...] Caused by: java.lang.NullPointerException at org.eclipse.ui.internal.provisional.views.markers.ExtendedMarkersView$10.runInUIThread(ExtendedMarkersView.java:896) at org.eclipse.ui.progress.UIJob$1.run(UIJob.java:94) at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35) at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:130) ... 52 more This brought down testResourceMappings(), but you just need to check getCategories() can return null. PW
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/provisional/views/markers/ExtendedMarkersView.java
return markers;
	}
	/**
	 * Add all concrete {@link MarkerItem} elements associated with the receiver
	 * to allMarkers.
	 * 
	 * @param markerItem
	 * @param allMarkers
	 */
	private void addAllConcreteItems(MarkerItem markerItem,
			Collection allMarkers) {
		if (markerItem.isConcrete()) {
			allMarkers.add(markerItem);
			return;
		}
		MarkerItem[] children = markerItem.getChildren();
		for (int i = 0; i < children.length; i++) {
			addAllConcreteItems(children[i], allMarkers);
		}
	}
	/**
	 * Return the group used for categorisation.
	 * 
	 * @return MarkerGroup
	 */
	MarkerGroup getCategoryGroup() {
		return builder.getCategoryGroup();
	}
	/**
	 * Return the clipboard for the receiver.