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
String propertyName = event.getProperty();
				if (propertyName
						.equals(IDEInternalPreferences.USE_MARKER_LIMITS)
						|| propertyName
								.equals(IDEInternalPreferences.MARKER_LIMITS_VALUE)) {
					viewer.refresh();
				}
			}
		};
		IDEWorkbenchPlugin.getDefault().getPreferenceStore()
				.addPropertyChangeListener(preferenceListener);
	}
	/**
	 * Add the category to the list of expanded categories.
	 * 
	 * @param category
	 */
	void addExpandedCategory(MarkerCategory category) {
		categoriesToExpand.add(category.getName());
	}
	/**
	 * Add all of the markers in markerItem recursively.
	 * 
	 * @param markerItem
	 * @param allMarkers
	 *            {@link Collection} of {@link IMarker}
	 */
	private void addMarkers(MarkerItem markerItem, Collection allMarkers) {
		if (markerItem.getMarker() != null)
			allMarkers.add(markerItem.getMarker());