Index: openacs-4/packages/categories/www/cadmin/tree-copy.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/categories/www/cadmin/tree-copy.tcl,v
diff -u -N -r1.15.2.1 -r1.15.2.2
--- openacs-4/packages/categories/www/cadmin/tree-copy.tcl	15 Mar 2019 11:21:40 -0000	1.15.2.1
+++ openacs-4/packages/categories/www/cadmin/tree-copy.tcl	29 Nov 2019 14:32:04 -0000	1.15.2.2
@@ -25,8 +25,8 @@
 set page_title [_ categories.Tree_copy_title]
 
 set context_bar [category::context_bar $tree_id $locale \
-                     [value_if_exists object_id] \
-                     [value_if_exists ctx_id]]
+                     [expr {[info exists object_id] ? $object_id : ""}] \
+                     [expr {[info exists ctx_id] ? $ctx_id : ""}]]
 lappend context_bar [_ categories.Tree_copy]
 
 template::multirow create trees tree_id tree_name site_wide_p view_url copy_url