覆盖设置器时出错

“公共矢量 SpeedVector”的“SpeedVector”出现“可访问性不一致”错误。

struct Vector
{
    public float x;
    public float y;

    public Vector(float x, float y)
    {
        this.x = x;
        this.y = y;
    }

    public static Vector operator +(Vector v1, Vector v2)
    {
        return new Vector(v1.x + v2.x, v1.y + v2.y);
    }
}
public class GameObject : Control
{
    public float mass;
    private Vector speedVector = new Vector(0, 0);

    public Vector SpeedVector
    {
        set
        {
            if (mass != 0)
            {
                speedVector = value;
            }
        }
        get => speedVector;
    }

    public void ElliminateCollision(GameObject obj1, GameObject obj2)
    {

    }

}