let something = SomeObject()

// Works as expected
something.someBlock = { print($0) }
something.someAction()

// Crashes 💥
something.someBlock = defaultBlock()
something.someAction()

// Works as expected
something.someBlock = Optional(defaultBlock())
something.someAction()

// Works as expected
something.someBlock = unsafeBitCast(defaultBlock(), to: SomeBlock.self)
something.someAction()