Index: trunk/src/org/openstreetmap/josm/gui/history/HistoryBrowserModel.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/history/HistoryBrowserModel.java	(revision 9676)
+++ trunk/src/org/openstreetmap/josm/gui/history/HistoryBrowserModel.java	(revision 9677)
@@ -231,5 +231,6 @@
 
     protected void initMemberListTableModels() {
-        if (current.getType() != OsmPrimitiveType.RELATION || reference.getType() != OsmPrimitiveType.RELATION)
+        if (current == null || current.getType() != OsmPrimitiveType.RELATION
+         || reference == null || reference.getType() != OsmPrimitiveType.RELATION)
             return;
         TwoColumnDiff diff = new TwoColumnDiff(