         if let value = maybeValue as? T {
           return .success(value)
         } else {
-          return .failure(.notConvertible("Could not convert \(maybeValue) to \(T.self)."))
+          return .failure(.notConvertible("Could not convert \(String(describing: maybeValue)) to \(T.self)."))
         }
       },
       set: {

        } else if maybeValue == nil {
          return .success(T(nilLiteral: ()))
        } else {
          return .failure(.notConvertible("Could not convert \(maybeValue) to \(T.self)."))
        }
      },
      set: {

        if let value = maybeValue as? T {
          return value
        } else {
          fatalError("Could not convert \(String(describing: maybeValue)) to \(T.self). Maybe `dynamic(keyPath:ofExpectedType:)` method might be of help?)")
        }
      },
      set: {
