Index: trunk/src/org/openstreetmap/josm/gui/dialogs/ConflictDialog.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/dialogs/ConflictDialog.java	(revision 5413)
+++ trunk/src/org/openstreetmap/josm/gui/dialogs/ConflictDialog.java	(revision 5414)
@@ -397,5 +397,8 @@
                 sel.add((OsmPrimitive)o);
             }
-            Main.main.getCurrentDataSet().setSelected(sel);
+            DataSet ds = Main.main.getCurrentDataSet();
+            if (ds != null) { // Can't see how it is possible but it happened in #7942 
+                ds.setSelected(sel);
+            }
         }