Index: trunk/src/org/openstreetmap/josm/data/osm/QuadBuckets.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/osm/QuadBuckets.java	(revision 2285)
+++ trunk/src/org/openstreetmap/josm/data/osm/QuadBuckets.java	(revision 2286)
@@ -887,6 +887,6 @@
     {
         QBLevel bucket = root.find_exact(n);
-        if (!bucket.isLeaf())
-            abort("found branch where leaf expected");
+        if (bucket == null)
+            return false;
         boolean ret = bucket.remove_content(n);
         return ret;