TCI - let getSelection return null instead of failing with NPE

Change-Id: I7000a633b654cb17e178575e586199f5ade678f7
diff --git a/bundles/org.eclipse.emf.emfstore.client.ui/src/org/eclipse/emf/emfstore/internal/client/ui/util/EMFStoreHandlerUtil.java b/bundles/org.eclipse.emf.emfstore.client.ui/src/org/eclipse/emf/emfstore/internal/client/ui/util/EMFStoreHandlerUtil.java
index 721aacb..f12ad4e 100644
--- a/bundles/org.eclipse.emf.emfstore.client.ui/src/org/eclipse/emf/emfstore/internal/client/ui/util/EMFStoreHandlerUtil.java
+++ b/bundles/org.eclipse.emf.emfstore.client.ui/src/org/eclipse/emf/emfstore/internal/client/ui/util/EMFStoreHandlerUtil.java
@@ -43,6 +43,9 @@
 	 */
 	@SuppressWarnings("unchecked")
 	public static <T> T getSelection(ExecutionEvent event, Class<T> clazz) {
+		if (event == null) {
+			return null;
+		}
 		ISelection sel = HandlerUtil.getCurrentSelection(event);
 		if (sel == null) {
 			sel = HandlerUtil.getActiveMenuSelection(event);