kebs-circe - StackOverflowError when deriving codecs using NoFlat variant

[pk044]

The problem can be reproduced with the test below (it should also be added to CirceFormatNoFlatTests along with the fix)

  object KebsProtocol extends KebsCirce with KebsCirce.NoFlat
  import KebsProtocol._

  case class R(a: Int, rs: Seq[R])

  test("Recursive format") {
    val decoder = implicitly[Decoder[R]]
    val encoder = implicitly[Encoder[R]]


    decoder.apply(
      Json
        .fromFields(Seq("a" -> Json.fromInt(1), "rs" -> Json.arr(Json.fromFields(Seq("a" -> Json.fromInt(2), "rs" -> Json.arr())))))
        .hcursor) shouldBe Right(R(1, Seq(R(2, Seq.empty[R]))))
    encoder.apply(R(1, Seq(R(2, Seq.empty[R])))) shouldBe Json.fromFields(
      Seq("a" -> Json.fromInt(1), "rs" -> Json.arr(Json.fromFields(Seq("a" -> Json.fromInt(2), "rs" -> Json.arr())))))
  }

Workaround: Add codecs using circe's semi-auto derivation. Example:

trait JsonProtocol
    extends FailFastCirceSupport
    with KebsCirce
    with KebsCirce.NoFlat
    with KebsEnumFormats
    with TimeInstances
    with UtilInstances
    with NetInstances {
  implicit val decoder: Decoder[Thing] = deriveDecoder[Thing]
  implicit val encoder: Encoder[Thing] = deriveEncoder[Thing]
}