Converting Play Json's JsLookupResult to Scalactic's Good Or Bad

RichJsLookupResult.scala

import org.scalactic._
import play.api.libs.json.{JsError, JsLookupResult, JsSuccess, Reads}

object RichJsLookupResult {

  implicit class RichPlayJsonValidateToGoodOrBad(lookupResult: JsLookupResult) {

    def parseAs[T](implicit rds: Reads[T]): T Or Every[String] = {
      lookupResult.validate[T] match {
        case s: JsSuccess[T] => Good(s.get)
        case e: JsError =>
          val errorMessages = e.errors.map {
            case (path, errors) if path.toString().trim != "" => path.toString() + ": " + errors.map(_.message).mkString(", ")
            case (_, errors) => errors.map(_.message).mkString(", ")
          }
          errorMessages.toList match {
            case Nil => throw new Exception(s"Error messages are expected but empty for $lookupResult")
            case msg :: Nil => Bad(One(msg))
            case h :: rest => Bad(Every(h, rest: _*))
          }
      }
    }
  }
}