Comment made by: monorok
I found an easier way to reproduce the problem:
(require '[clojure.core.async :as async :refer [go <!]])</p>
(def ^:dynamic d)
(binding [d :bound]
(<! (async/timeout 10))
object[clojure.lang.Var$Unbound 0x15f8a952 Unbound: #'user/d]
Unfortunately I don't know how to edit the description of an issue.