Index: applications/editors/josm/plugins/mapillary/src/org/openstreetmap/josm/plugins/mapillary/MapillaryData.java
===================================================================
--- applications/editors/josm/plugins/mapillary/src/org/openstreetmap/josm/plugins/mapillary/MapillaryData.java	(revision 31452)
+++ applications/editors/josm/plugins/mapillary/src/org/openstreetmap/josm/plugins/mapillary/MapillaryData.java	(revision 31453)
@@ -38,5 +38,6 @@
     addListener(MapillaryPlugin.zoomAction);
     addListener(MapillaryPlugin.uploadAction);
-    addListener(MapillaryMainDialog.getInstance());
+    if (Main.main != null)
+      addListener(MapillaryMainDialog.getInstance());
   }