Index: src/org/openstreetmap/josm/data/imagery/ImageryInfo.java
===================================================================
--- src/org/openstreetmap/josm/data/imagery/ImageryInfo.java	(revision 16569)
+++ src/org/openstreetmap/josm/data/imagery/ImageryInfo.java	(working copy)
@@ -788,7 +788,7 @@
      * @see SourceInfo#getSourceType
      */
     public ImageryType getImageryType() {
-        return super.getSourceType();
+        return super.getSourceType() == null ? ImageryType.WMS.getDefault() : super.getSourceType();
     }
 
     /**