Index: /trunk/src/org/openstreetmap/josm/gui/tagging/TaggingPreset.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/tagging/TaggingPreset.java	(revision 5159)
+++ /trunk/src/org/openstreetmap/josm/gui/tagging/TaggingPreset.java	(revision 5160)
@@ -123,7 +123,8 @@
                     return CLOSEDWAY;
                 case RELATION:
+                case MULTIPOLYGON:
                     return RELATION;
                 default:
-                    throw new IllegalArgumentException();
+                    throw new IllegalArgumentException("Unexpected primitive type: " + type);
             }
         }