当传递T时，为什么Pick<T，K>没有抛出错误？

type Pick<T, K extends keyof T> = {
    [P in K]: T[P];
};

type Pick<T, K extends keyof T> = {
    [P in K]: T[P];
};

function pickProperties<T, K extends keyof T>(obj: T, keys: K[]): Pick<T, K> {
    const result = {} as Pick<T, K>;
    for (const key of keys) {
        if (key in obj) {
            result[key] = obj[key];
        } else {
            throw new Error(`Property '${key}' does not exist in object.`);
        }
    }
    return result;
}

// Example usage
const obj = { name: "John", age: 30, city: "New York" };
const picked = pickProperties(obj, ["name", "age", "gender"]); // Throws an error