Index: /trunk/src/org/openstreetmap/josm/gui/progress/PleaseWaitProgressMonitor.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/progress/PleaseWaitProgressMonitor.java	(revision 5825)
+++ /trunk/src/org/openstreetmap/josm/gui/progress/PleaseWaitProgressMonitor.java	(revision 5826)
@@ -312,5 +312,7 @@
             @Override
             public void run() {
-                dialog.setInBackgroundPossible(PleaseWaitProgressMonitor.this.taskId != null && Main.isDisplayingMapView());
+                if (dialog != null) {
+                    dialog.setInBackgroundPossible(PleaseWaitProgressMonitor.this.taskId != null && Main.isDisplayingMapView());
+                }
             }
         });