Index: /trunk/src/org/openstreetmap/josm/actions/CloseChangesetAction.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/actions/CloseChangesetAction.java	(revision 15341)
+++ /trunk/src/org/openstreetmap/josm/actions/CloseChangesetAction.java	(revision 15342)
@@ -100,5 +100,7 @@
         protected void cancel() {
             this.canceled = true;
-            reader.cancel();
+            if (reader != null) {
+                reader.cancel();
+            }
         }