Fix to allow existential type to function arguments

[yoshiki-tsukada]

Related #90

Hello, thank you for developing a great OSS!
I fixed a bug that occurred when function arguments contained an existential type.

The following code causes an error.

@Spyable
protocol ViewModelProtocol {
    func foo(model: any ModelProtocol)
}

class ViewModelProtocolSpy: ViewModelProtocol {
    var fooModelCallsCount = 0
    var fooModelCalled: Bool {
        return fooModelCallsCount > 0
    }
    var fooModelReceivedModel: any ModelProtocol? // ❌ Optional 'any' type must be written '(any ModelProtocol)?'
    var fooModelReceivedInvocations: [any ModelProtocol] = []
    var fooModelClosure: ((any ModelProtocol) -> Void)?
    func foo(model: any ModelProtocol) {
        fooModelCallsCount += 1
        fooModelReceivedModel = (model)
        fooModelReceivedInvocations.append((model))
        fooModelClosure?(model)
    }
}

It needs to be like this.

class ViewModelProtocolSpy: ViewModelProtocol {
    var fooModelCallsCount = 0
    var fooModelCalled: Bool {
        return fooModelCallsCount > 0
    }
    var fooModelReceivedModel: (any ModelProtocol)? // ✅
    var fooModelReceivedInvocations: [any ModelProtocol] = []
    var fooModelClosure: ((any ModelProtocol) -> Void)?
    func foo(model: any ModelProtocol) {
        fooModelCallsCount += 1
        fooModelReceivedModel = (model)
        fooModelReceivedInvocations.append((model))
        fooModelClosure?(model)
    }
}

[Matejkob]

Hi @yoshiki-tsukada,

thanks so much for the contribution!

The changes look good!