Index: /applications/editors/josm/plugins/terracer/src/terracer/TerracerAction.java
===================================================================
--- /applications/editors/josm/plugins/terracer/src/terracer/TerracerAction.java	(revision 30126)
+++ /applications/editors/josm/plugins/terracer/src/terracer/TerracerAction.java	(revision 30127)
@@ -464,5 +464,5 @@
             public boolean executeCommand() {
                 boolean result = super.executeCommand();
-                if (result) {
+                if (result && tagsInConflict != null) {
                     try {
                         // Build conflicts commands only after all primitives have been added to dataset to fix #8942