Fails with Should not return a non-failure

[copy]

The following simplified test fails with Fatal error: exception Failure("Should not return a non-failure"):

let () =
  let open Popper in
  let open Sample.Syntax in
  run (test (fun () ->
      let* a = Sample.array Sample.int in
      let+ b = Sample.array Sample.int in
      let t1 = Array.append a b in
      let t2 = Array.append b a in
      Proposition.equal Comparator.(array int) t1 t2
    ))

[jobjo]

Thanks, will take a look.