Index: /trunk/src/org/openstreetmap/josm/actions/MergeNodesAction.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/actions/MergeNodesAction.java	(revision 13188)
+++ /trunk/src/org/openstreetmap/josm/actions/MergeNodesAction.java	(revision 13189)
@@ -297,5 +297,9 @@
         Set<Node> allNodes = new HashSet<>(nodes);
         allNodes.add(targetLocationNode);
-        return mergeNodes(nodes, selectTargetNode(allNodes), targetLocationNode);
+        Node targetNode = selectTargetNode(allNodes);
+        if (targetNode == null) {
+            return null;
+        }
+        return mergeNodes(nodes, targetNode, targetLocationNode);
     }
 
Index: /trunk/src/org/openstreetmap/josm/actions/mapmode/SelectAction.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/actions/mapmode/SelectAction.java	(revision 13188)
+++ /trunk/src/org/openstreetmap/josm/actions/mapmode/SelectAction.java	(revision 13189)
@@ -719,5 +719,7 @@
                     if (ll != null && ll.isOutSideWorld()) {
                         // Revert move
-                        ((MoveCommand) c).resetToCheckpoint();
+                        if (c instanceof MoveCommand) {
+                            ((MoveCommand) c).resetToCheckpoint();
+                        }
                         // TODO: We might use a simple notification in the lower left corner.
                         JOptionPane.showMessageDialog(