(def conn (d/create-conn {:root/elements {:db.cardinality :db.cardinality/many
                                            :db/valueType :db.type/ref}}))

(d/transact conn [[:db/add 0 :root {}]
                  [:db/add 1 :element {}]
                  [:db/add 2 :element {}]
                  [:db/add 0 :root/elements 1]
                  [:db/add 0 :root/elements 2]])

(d/pull @conn '[(limit :root/elements nil)] 0)
;works
(d/pull @conn '[(limit :root/elements 3)] 0)
;works too
(d/pull @conn '[(limit :root/elements 0)] 0)
;errors but probably is intentional
(d/pull @conn '[(limit :root/elements 2)] 0)
;errors but might be a bug?
;#object[Error Error: No protocol method ITransientCollection.-persistent! defined for type cljs.core/Reduced: [object Object]]