Default value on recursive inductive error

Stream: lean4

[Yuri de Wit]

Consider the following inductive, which works fine:

inductive Value
| mk (data: Float) (prev : Option (Value × Value)) (op: Option Op := .none) (label : Option String := "") (grad : Float)
deriving Repr

When I add a default value to prev:

inductive Value
| mk (data: Float) (prev : Option (Value × Value) := .none) (op: Option Op := .none) (label : Option String := "") (grad : Float)
deriving Repr

I get the following error:

application type mismatch
  optParam _nested.Option_1 none
argument has type
  Option _nested.Prod_2
but function has type
  _nested.Option_1 → Type

I can't make much sense out of it. Any ideas?