Regex Error

I've been trying out klipse and I think I found a bug?

To reproduce go this page:
http://app.klipse.tech/?container&cljs_in.gist=viebel/f5e8fb5f4c6a33fd7b9a758cc2cdf549

and paste this input:

(defn re-groups
  [re s]
  (if (string? s)
    (let [matches (.exec re s)]
      (when (= (first matches) s)
        (if (.-groups matches)
          (.-groups matches)
          (throw (js/TypeError. "re-groups must contain a group.")))))
    (throw (js/TypeError. "re-groups must match against a string."))))

(re-groups #"(?<P>.+?)$" "A Test String")

I get the exception below:

klipse.js?version=7.3.2:21130 Uncaught TypeError: Cannot read property 'cljs$lang$ctorStr' of undefined
    at Object.cljs.core.pr_writer_impl (klipse.js?version=7.3.2:21130)
    at Object.cljs.core.pr_writer (klipse.js?version=7.3.2:21142)
    at Object.cljs.core.pr_seq_writer (klipse.js?version=7.3.2:21145)
    at Object.cljs.core.pr_sb_with_opts (klipse.js?version=7.3.2:21164)
    at Object.cljs.core.pr_str_with_opts (klipse.js?version=7.3.2:21169)
    at Function.cljs.core.pr_str.cljs$core$IFn$_invoke$arity$variadic (klipse.js?version=7.3.2:21219)
    at cljs.pprint.pprint_simple_default (klipse.js?version=7.3.2:34183)
    at cljs.core.MultiFn.cljs$core$IFn$_invoke$arity$1 (klipse.js?version=7.3.2:22840)
    at Object.cljs.pprint.write_out (klipse.js?version=7.3.2:32318)
    at Function.cljs.pprint.pprint.cljs$core$IFn$_invoke$arity$2 (klipse.js?version=7.3.2:32413)

I finally ended up testing it in figwheel and it seems to work fine.