From 2fe0a5aa7a90c121d708af24fd4ef7a20aec2948 Mon Sep 17 00:00:00 2001
From: odow <o.dowson@gmail.com>
Date: Mon, 30 Oct 2023 12:38:03 +1300
Subject: [PATCH] Fix

---
 src/aff_expr.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/aff_expr.jl b/src/aff_expr.jl
index 636e3a70209..cfb54aaef51 100644
--- a/src/aff_expr.jl
+++ b/src/aff_expr.jl
@@ -824,7 +824,7 @@ function _eval_as_variable(f::F, x::GenericAffExpr, args...) where {F}
             "Cannot call $f with $x because it is not a real-valued affine " *
             "expression of one variable.",
         )
-    elseif !isone(first(keys(x.terms)))
+    elseif !isone(first(values(x.terms)))
         error(
             "Cannot call $f with $x because it is not a real-valued affine " *
             "expression of one variable with a coefficient of `+1`.",