public T takeout() { if (num > 0) { num--; } 报错

public class cage<T>
    {
        T[] array;
        readonly int size;
        int num;
        public cage(int n)
        {
            size = n;
            num = 0;
            array = new T[size];
        }
        public void putin(T pet)
        {
            if (num < size)
            {
                array[num++] = pet;
            }
            else
                Console.WriteLine("笼子已装满！");
        }
        public T takeout()
        {
            if (num > 0)
            {
               num--;
            }
            else
            {
                Console.WriteLine("笼子是空的！");
                return default(T);
            }
        }

    }

public T takeout()报错：并不是所有路径都有返回值？？？，需要怎么修改呢