try to avoid obscure runtime error on prod only :sigh:

https://github.com/playframework/playframework/issues/7508

build.sbt

@@ -28,6 +28,7 @@ externalizeResources := false
 scriptClasspath := Seq("*")
 // offline := true
 libraryDependencies ++= Seq(
+  ws,
   play.jodaJson, play.jodaForms, play.iteratee, play.streams,
   scalaz, chess, scalalib, hasher, typesafeConfig, findbugs,
   reactivemongo.driver, reactivemongo.iteratees, akka.actor,

modules/search/src/main/ESClient.scala

@@ -1,6 +1,8 @@
 package lila.search
 
 import play.api.libs.json._
+import play.api.libs.ws.JsonBodyReadables._
+import play.api.libs.ws.JsonBodyWritables._
 
 sealed trait ESClient {