Plumbing: missing key error message

foo.clj

(ns foo
  (:require [plumbing.core :refer [fnk]]
            [plumbing.graph :as graph]))

(defn service1
  []
  {:service1 (fnk [[:non-existent-service foo]]
                  {:bar (fn [] (println "BAR!"))})})

(let [compiled (graph/eager-compile (service1))]
  (compiled {})
  (println "yo"))

;; => RuntimeException Key :non-existent-service not found in null  plumbing.fnk.impl/safe-get (impl.clj:38)