Index: src/org/openstreetmap/josm/data/osm/QuadBuckets.java
===================================================================
--- src/org/openstreetmap/josm/data/osm/QuadBuckets.java	(revision 2285)
+++ src/org/openstreetmap/josm/data/osm/QuadBuckets.java	(working copy)
@@ -886,8 +886,8 @@
     public boolean remove(T n)
     {
         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;
     }