Index: trunk/src/org/openstreetmap/josm/data/osm/visitor/paint/relations/Multipolygon.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/osm/visitor/paint/relations/Multipolygon.java	(revision 11312)
+++ trunk/src/org/openstreetmap/josm/data/osm/visitor/paint/relations/Multipolygon.java	(revision 11313)
@@ -170,6 +170,6 @@
         /**
          * Constructs a new {@code JoinedWay}.
-         * @param nodes list of nodes
-         * @param wayIds list of way IDs
+         * @param nodes list of nodes - must not be null
+         * @param wayIds list of way IDs - must not be null
          * @param selected whether joined way is selected or not
          */
@@ -606,5 +606,7 @@
             }
 
-            result.add(new JoinedWay(nodes, wayIds, selected));
+            if (nodes != null) {
+                result.add(new JoinedWay(nodes, wayIds, selected));
+            }
         }