check for NULL error return in idset test
diff --git a/regress/idset/idset_test.c b/regress/idset/idset_test.c
index de713b3..4d14cc7 100644
--- a/regress/idset/idset_test.c
+++ b/regress/idset/idset_test.c
@@ -104,6 +104,8 @@ idset_add_remove_iter(void)
if (err)
goto done;
err = got_object_idset_add(set, &id2, NULL);
+ if (err == NULL)
+ abort();
if (err->code != GOT_ERR_OBJ_EXISTS)
goto done;
err = NULL;