Index: src/org/openstreetmap/josm/data/validation/tests/UnconnectedWays.java
===================================================================
--- src/org/openstreetmap/josm/data/validation/tests/UnconnectedWays.java	(revision 15353)
+++ src/org/openstreetmap/josm/data/validation/tests/UnconnectedWays.java	(working copy)
@@ -454,6 +454,7 @@
                             nextNodes.add(way.getNode(pos + 1));
                         }
                         for (Node next : nextNodes) {
+                            if (next == null || !next.isLatLonKnown()) continue;
                             final boolean containsN = visited.contains(next);
                             visited.add(next);
                             if (!containsN && isConnectedTo(next, way, visited,