getting warning: CS8618 - Non-nullable variable must contain a non-null value when exiting construct

truct Rectangle<T> 
{
    T length;
    T width;

    public T Length{
        readonly get{ return length; }
        set{ length = value; }
    }
    public T Width{
        readonly get{ return width; }
        set{ width = value; }
    }

    public Rectangle(T L, T W) // <-- this is where I am getting the warning
    {
        Length = L;
        Width = W;
    }
}