patch 8.2.4225: Vim9: depth argument of :lockvar not parsed in :def function

Problem:    Vim9: depth argument of :lockvar not parsed in :def function.
Solution:   Parse the optional depth argument. (closes #9629)
            Fix that locking doesn't work for a non-materialize list.
diff --git a/src/errors.h b/src/errors.h
index d89c27c..dd1b9fc 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -2859,10 +2859,10 @@
 	INIT(= N_("E1116: \"assert_fails()\" fifth argument must be a string"));
 EXTERN char e_cannot_use_bang_with_nested_def[]
 	INIT(= N_("E1117: Cannot use ! with nested :def"));
-EXTERN char e_cannot_change_list[]
-	INIT(= N_("E1118: Cannot change list"));
-EXTERN char e_cannot_change_list_item[]
-	INIT(= N_("E1119: Cannot change list item"));
+EXTERN char e_cannot_change_locked_list[]
+	INIT(= N_("E1118: Cannot change locked list"));
+EXTERN char e_cannot_change_locked_list_item[]
+	INIT(= N_("E1119: Cannot change locked list item"));
 EXTERN char e_cannot_change_dict[]
 	INIT(= N_("E1120: Cannot change dict"));
 EXTERN char e_cannot_change_dict_item[]