Bug 299209 [CommonNavigator] Clean up error reporting for pipelined extensions
A catch block was missing for one of them, and the error report does not provide the extension Id that had the problem.
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/NavigatorPipelineService.java
* For content extensions that reshape the structure of children in a
	 * viewer, their overridden extensions may sometimes use optimized refreshes
	 * to add elements to the tree. These attempts must be intercepted and
	 * mapped to the correct set of model elements in the overriding extension.
	 * Clients may add, remove, or modify elements in the given set of added
	 * children. Clients should return a set for downstream extensions to
	 * massage further.
	 * </p>
	 * <p>
	 * <b>Clients should not call any of the add, remove, refresh, or update
	 * methods on the viewer from this method or any code invoked by the
	 * implementation of this method.</b>
	 * </p>
	 * 
	 * @param anAddModification
	 *            The shape modification which contains the current suggested
	 *            parent and children. Clients may modify this parameter
	 *            directly and return it as the new shape modification.
	 * @return The new shape modification to use. Clients should <b>never</b>
	 *         return <b>null</b> from this method.
	 */
	public PipelinedShapeModification interceptAdd(
			PipelinedShapeModification anAddModification) {
		
		ContributorTrackingSet trackedSet =(ContributorTrackingSet) anAddModification.getChildren();
		
		Set contentDescriptors = contentService.findDescriptorsByTriggerPoint(anAddModification.getParent(), !NavigatorContentService.CONSIDER_OVERRIDES);
		
		
		for (Iterator descriptorsItr = contentDescriptors.iterator(); descriptorsItr.hasNext();) {