Index: trunk/test/unit/org/openstreetmap/josm/gui/dialogs/relation/actions/RelationEditorActionsTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/gui/dialogs/relation/actions/RelationEditorActionsTest.java	(revision 19011)
+++ trunk/test/unit/org/openstreetmap/josm/gui/dialogs/relation/actions/RelationEditorActionsTest.java	(revision 19014)
@@ -17,4 +17,5 @@
 import org.openstreetmap.josm.data.coor.LatLon;
 import org.openstreetmap.josm.data.osm.DataSet;
+import org.openstreetmap.josm.data.osm.IRelation;
 import org.openstreetmap.josm.data.osm.Node;
 import org.openstreetmap.josm.data.osm.Relation;
@@ -169,5 +170,10 @@
         relationEditorAccess.getTagModel().initFromPrimitive(relation);
         relationEditorAccess.getEditor().reloadDataFromRelation();
-        assertDoesNotThrow(relationEditorAccess::getChangedRelation);
+
+        assertDoesNotThrow(() -> {
+            IRelation<?> tempRelation = relationEditorAccess.getChangedRelation();
+            if (tempRelation.getDataSet() == null)
+                tempRelation.setMembers(null); // see #19885
+        });
     }
 }