Помогите решить проблему. Код выдает System.NullReferenceException: "Ссылка на объект не указывает на экземпляр объекта". Не могу понять что не так

Question

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Keyboard
{
    public partial class Move : Form
    {

        public Move()
        {
            InitializeComponent();
        }
        Graphics gr;
        BufferedGraphics bg;                              
        BufferedGraphicsContext bufferedGraphicsContext;  
        Pen Black = new Pen(Color.Black, 4);
        Pen Red = new Pen(Color.Red, 5);
        RectangleF player1 = new RectangleF(575.0F, 20.0F, 60.0F, 100.0F);
        RectangleF player2 = new RectangleF(50.0F, 500.0F, 90.0F, 20.0F);
        Rectangle bar = new Rectangle(400, 40, 70, 100);

        void Move_SizeChanged(object sender, EventArgs e)

        {
            InitializeComponent();
            Size = new Size(800, 680);
            StartPosition = FormStartPosition.CenterScreen;


            KeyDown += new KeyEventHandler(Move_KeyDown); 
            Paint += new PaintEventHandler(Move_Paint);  
            SizeChanged += new EventHandler(Move_SizeChanged);

            bufferedGraphicsContext = BufferedGraphicsManager.Current;

            InitializeGraphics();
        }

        private void Move_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Left)
                player1.Location = new PointF(player1.Left - 10, player1.Top);

            if (e.KeyCode == Keys.Right)
                player1.Location = new PointF(player1.Left + 10, player1.Top);
            if (e.KeyCode == Keys.Up)
                player1.Location = new PointF(player1.Left, player1.Top - 10);
            if (e.KeyCode == Keys.Down)
                player1.Location = new PointF(player1.Left, player1.Top + 10);
            if (e.KeyCode == Keys.A)
                player2.Location = new PointF(player2.Left - 10, player2.Top);
            if (e.KeyCode == Keys.D)
                player2.Location = new PointF(player2.Left + 10, player2.Top);
            if (e.KeyCode == Keys.W)
                player2.Location = new PointF(player2.Left, player2.Top - 10);
            if (e.KeyCode == Keys.S)
                player2.Location = new PointF(player2.Left, player2.Top + 10);


            if (player1.IntersectsWith(player2) || player2.IntersectsWith(player1))
            {
                MessageBox.Show;
                Environment.Exit(0);
            }

            if (player2.Top > 535 || player2.Top < 0 || player2.Right > 780 || player2.Right < 85)
            {
                player2.Location = new PointF(player2.Location.X - 15, player2.Location.Y);

            }

            if (player1.Top > 535 || player1.Top < 0 || player1.Right > 780 || player1.Right < 50)
            {
                player1.Location = new PointF(player1.Location.X - 15, player1.Location.Y);
            }
            if (player1.IntersectsWith(bar))
            {
                player1.Location = new PointF(player1.Location.X + 10, player1.Location.Y);
                player1.Location = new PointF(player1.Location.X, player1.Location.Y + 10);

            }
            if (player1.IntersectsWith(bar))
            {
                player1.Location = new PointF(player1.Location.X - 20, player1.Location.Y);
                player1.Location = new PointF(player1.Location.X, player1.Location.Y - 10);
            }
            if (player2.IntersectsWith(bar))
            {
                player2.Location = new PointF(player2.Location.X + 10, player2.Location.Y);
                player2.Location = new PointF(player2.Location.X, player2.Location.Y + 10);
            }
            if (player2.IntersectsWith(bar))
            {
                player2.Location = new PointF(player2.Location.X - 20, player2.Location.Y);
                player2.Location = new PointF(player2.Location.X, player2.Location.Y - 10);
            }

            Refresh();
        }

        private void Move_Paint(object sender, PaintEventArgs e)
        {
            DrawToBuffer();
        }
        private void DrawToBuffer()
        {
            bg.Graphics.Clear(BackColor); //Проблема с этой строкой. Выдает  System.NullReferenceException: "Ссылка на объект не указывает на экземпляр объекта"
            bg.Graphics.DrawEllipse(Black, player1);
            bg.Graphics.DrawEllipse(Black, player2);

            SolidBrush red = new SolidBrush(Color.Red);
            SolidBrush black = new SolidBrush(Color.Black);
            bg.Graphics.DrawRectangle(Red, bar);
            bg.Graphics.FillRectangle(red, bar);
            bg.Graphics.FillEllipse(black, player1);
            bg.Graphics.FillEllipse(black, player2);
            bg.Render();
        }
        private void InitializeGraphics()
        {
            gr = CreateGraphics();
            bg = bufferedGraphicsContext.Allocate(gr, ClientRectangle);
        }
    }
    }

Answer 1

private void DrawToBuffer()
        {
            if(bg==null)return;
            bg.Graphics.Clear(BackColor); //Проблема с этой строкой. Выдает  System.NullReferenceException: "Ссылка на объект не указывает на экземпляр объекта"
            bg.Graphics.DrawEllipse(Black, player1);
            bg.Graphics.DrawEllipse(Black, player2);

            SolidBrush red = new SolidBrush(Color.Red);
            SolidBrush black = new SolidBrush(Color.Black);
            bg.Graphics.DrawRectangle(Red, bar);
            bg.Graphics.FillRectangle(red, bar);
            bg.Graphics.FillEllipse(black, player1);
            bg.Graphics.FillEllipse(black, player2);
            bg.Render();
        }