From 0dd32d46bf3f9abc73be2b02e235b32c9ee9383d Mon Sep 17 00:00:00 2001
From: Sebastian Funk <sebastian.funk@lshtm.ac.uk>
Date: Wed, 24 Apr 2024 21:41:28 +0100
Subject: [PATCH] handle backend correctly in opts

---
 R/opts.R | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/R/opts.R b/R/opts.R
index cf24eaba1..17cfe8eca 100644
--- a/R/opts.R
+++ b/R/opts.R
@@ -983,11 +983,13 @@ stan_opts <- function(object = NULL,
     } else {
       stop("`object` must be a stan model object")
     }
+  } else {
+    backend <- arg_match(backend, values = c("rstan", "cmdstanr"))
+    opts <- c(opts, list(backend = backend))
   }
   opts <- c(opts, list(
     object = object,
-    method = method,
-    backend = backend
+    method = method
   ))
   if (method == "sampling") {
     opts <- c(