Error when using ... and not _

[CarlOlson]

Playground: https://rescript-lang.org/try?version=v12.0.0-beta.12&module=esmodule&code=C4TwDgpgBMBQsQB7AgJwHYEMA2MBcMUAvFAETCnxIoY5SYAmDAEgPasDWBAFMADRQA5JmIA+KAFd0AS2ABKMZJnBiZRi3YdKsbBBXq2nAIyqDm3gID6c+Lv1NDHAEymH5-lAB03m0A

Code:

type t

external t: t = "t"

external addHook: (t, 'a => unit) => unit = "addHook"

// okay
let addHook1 = addHook(t, _)

// error
let addHook2 = addHook(t, ...)

Error:

[E] Line 9, column 4:

This expression's type contains type variables that cannot be generalized:
  ('_weak5 => unit) => unit
  
  This happens when the type system senses there's a mutation/side-effect,
  in combination with a polymorphic value.
  Using or annotating that value usually solves it.

Versions tested: 11.x and 13.0.0-alpha.3

In this example I would expect that both _ and ... behave the same.