Swift type inference bug

class Stub<ArgumentsType> {
    let argumentsMatcher: ArgumentsType -> Bool
    
    init(matcher: ArgumentsType -> Bool) {
        self.argumentsMatcher = matcher
    }
}

var stubs = [Any]()

let stub1 = Stub<String>(matcher: { (arg: String) -> Bool in
    return true
})

let stub2 = Stub<String>(matcher: { (arg: String) -> Bool in
    return true
})

stubs = [stub1, stub2]

//this crashes on second iteration
if let stubs = stubs as? [Stub<String>] {
    for stub in stubs {
        stub.argumentsMatcher("some string")
    }
}

//this works
for stub in stubs {
    if let typedStub = stub as? Stub<String> {
        typedStub.argumentsMatcher("some string")
    }
}