Closes #909

crates/aiken-project/src/test_framework.rs

@@ -1128,10 +1128,16 @@ impl Assertion<UntypedExpr> {
                 .to_string()
         };
 
+        // head did not map to a constant
         if self.head.is_err() {
             return red("program failed");
         }
 
+        // any value in tail did not map to a constant
+        if self.tail.is_err() {
+            return red("program failed");
+        }
+
         fn fmt_side(side: &UntypedExpr, stream: Stream) -> String {
             let __ = "│".if_supports_color(stream, |s| s.red());