Index: trunk/src/org/openstreetmap/josm/gui/dialogs/RelationListDialog.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/dialogs/RelationListDialog.java	(revision 5516)
+++ trunk/src/org/openstreetmap/josm/gui/dialogs/RelationListDialog.java	(revision 5517)
@@ -761,4 +761,5 @@
 
         public Object getElementAt(int index) {
+            if (index < 0 || index >= relations.size()) return null;
             return relations.get(index);
         }