val providers fail with @named and subclasses

[yurique]

import factorio._

object FactorioTest {

  trait Thing

  class WantNamedSomething(@named("volde") val some: Thing)

  @blueprint
  class TestBlueprint {
    @provides @named("volde")
    val thing: Thing = new Thing {}
// if changed to 
//
//   def thing: Thing = new Thing {}
//
// it works
  }

  val assembler = Assembler[WantNamedSomething](new TestBlueprint)
  assembler()

}

results in this error:

[error]
[error]  [Factorio]: Cannot construct an instance of an abstract class [FactorioTest.Thing named volde], provide a concrete class binder or an instance provider.
[error]
[error] While analyzing path:
[error] 0: io.saa.front.FactorioTest.WantNamedSomething ->
[error]
[error]   val assembler = Assembler[WantNamedSomething](new TestBlueprint)
[error]                                                ^

[yurique]

Also, if Thing is a class Thing and the val is assigned to new Thing (instead of subclassing with new Thing {}) -- val works as well.