Allow the tree to drop successfully outside its own scope without causing the internal tree structure to become corrupt

Author: bpneal

src/react-sortable-tree.js

@@ -262,7 +262,7 @@ class ReactSortableTree extends Component {
     }
 
     endDrag(dropResult) {
-        if (!dropResult) {
+        if (!dropResult || !dropResult.node) {
             return this.setState({
                 draggingTreeData: null,
                 swapFrom: null,