Index: /trunk/src/org/openstreetmap/josm/gui/dialogs/CommandStackDialog.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/dialogs/CommandStackDialog.java	(revision 16788)
+++ /trunk/src/org/openstreetmap/josm/gui/dialogs/CommandStackDialog.java	(revision 16789)
@@ -430,6 +430,8 @@
             } else if (!redoTree.isSelectionEmpty()) {
                 path = redoTree.getSelectionPath();
-            } else
-                throw new IllegalStateException();
+            } else {
+                // see #19514 for a possible cause
+                return;
+            }
 
             DataSet dataSet = MainApplication.getLayerManager().getEditDataSet();