unity - not all code paths return a value

I created a method in my spawn manager trying to get the maximum and minimum with of spawn to be within the screen but i keep on getting the error

error CS0161: `SpawnManager.GetRandomPointOnScreen()': not all code paths return a value

does anyone have an idea as to what might be causing this error

 Vector3 GetRandomPointOnScreen()

        {

            Camera camera = Camera.main;
            float halfHeight = camera.orthographicSize;
            float halfWidth = camera.aspect * halfHeight;

            float horizontalMin = -halfWidth;
            float horizontalMax =  halfWidth;



        }