argonaut 6.1-M5 stack overflow

package msw.util

import org.joda.time.DateTime
import org.joda.time.format.ISODateTimeFormat

import argonaut._
import argonaut.Argonaut._

object Codecs {

  implicit def DateTimeJsonCodec: CodecJson[DateTime] = CodecJson(
    dt => jString(dt.toString(ISODateTimeFormat.dateTime)),
    c  => c.as[String].map(ISODateTimeFormat.dateTime.parseDateTime)
  )

}