Index: trunk/src/org/openstreetmap/josm/gui/progress/PleaseWaitProgressMonitor.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/progress/PleaseWaitProgressMonitor.java	(revision 4760)
+++ trunk/src/org/openstreetmap/josm/gui/progress/PleaseWaitProgressMonitor.java	(revision 4761)
@@ -274,15 +274,17 @@
             @Override
             public void run() {
-                dialog.setVisible(false);
-                dialog.setCancelCallback(null);
-                dialog.setInBackgroundCallback(null);
-                dialog.removeWindowListener(windowListener);
-                dialog.dispose();
-                dialog = null;
-                MapFrame map = Main.map;
-                if (map != null) {
-                    map.statusLine.progressMonitor.setVisible(false);
-                }
-                Main.currentProgressMonitor = null;
+                if (dialog != null) {
+                    dialog.setVisible(false);
+                    dialog.setCancelCallback(null);
+                    dialog.setInBackgroundCallback(null);
+                    dialog.removeWindowListener(windowListener);
+                    dialog.dispose();
+                    dialog = null;
+                    Main.currentProgressMonitor = null;
+                    MapFrame map = Main.map;
+                    if (map != null) {
+                        map.statusLine.progressMonitor.setVisible(false);
+                    }
+                }
             }
         });