“无法调用可能是'未定义'的对象”即使在确保它之后！==未定义

为什么Cannot invoke an object which is possibly 'undefined'即使在我检查func引用不是未定义的之后，我也会收到Typescript 错误？

type Hoge = {
    func?: (str: string) => boolean
}

const myFunc = (obj: Hoge) => {
    const data = ['AAA', 'BBB', 'CCC']

    if(obj.func !== undefined) {
        data.filter(obj.func) // ok
        data.filter(v => obj.func(v)) // ng Cannot invoke an object which is possibly 'undefined'.
    }
}