有没有办法在Circe解码器中有可选的字段？

import io.circe._
import io.circe.parser._

case class Person(name: String, age: Option[Int])

object Person {
  implicit val decoder: Decoder[Person] = (c: HCursor) =>
    for {
      name <- c.downField("name").as[String]
      age <- c.downField("age").as[Option[Int]]
    } yield Person(name, age)
}

val json = """{"name": "John", "age": 30}"""
val person = decode[Person](json)

person match {
  case Right(p) => println(p)
  case Left(error) => println(error.getMessage)
}