From 3286e78cd2057a407dcfc54a74835854f0abb9dc Mon Sep 17 00:00:00 2001
From: Mark Thom <markjordanthom@gmail.com>
Date: Sun, 26 Feb 2023 16:29:39 -0700
Subject: [PATCH] third argument of copy_term should be instantiated as a list
 (#1747)

---
 src/machine/project_attributes.pl | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/machine/project_attributes.pl b/src/machine/project_attributes.pl
index 59ad0790..20a19e97 100644
--- a/src/machine/project_attributes.pl
+++ b/src/machine/project_attributes.pl
@@ -111,7 +111,11 @@ delete_all_attributes_from_var(V) :- '$delete_all_attributes_from_var'(V).
 
 copy_term(Term, Copy, Gs) :-
    can_be(list, Gs),
-   findall(Term-Rs, term_residual_goals(Term,Rs), [Copy-Gs]).
+   findall(Term-Rs, term_residual_goals(Term,Rs), [Copy-Gs]),
+   (  var(Gs) ->
+      Gs = []
+   ;  true
+   ).
 
 term_residual_goals(Term,Rs) :-
     '$term_attributed_variables'(Term, Vs),
-- 
2.54.0