I’m trying to upload an image but I can’t. (beginner)

Question

While I was doing a course of games for java, I was trying to load a Sprite/image and the following error appeared on the console

Exception in thread "main" java.lang.NullPointerException
at DracCastle.Cenarie.getSprite(Cenarie.java:24)

I have two classes, this is the code of the first:

package DracCastle;

import java.awt.Canvas;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.image.BufferStrategy;
import java.awt.image.BufferedImage;
import javax.swing.JFrame;
import DracCastle.TheGame;

public class TheGame extends Canvas implements Runnable{

public static JFrame frame;
private boolean isRunning = true;
private Thread thread;
private final int WIDTH = 1280;
private final int HEIGHT = 720;
private final int SCALE = 1;

private Cenarie skynight;
private BufferedImage background;

public TheGame(){
    skynight = new Cenarie("/SkyNight.png");
    background = skynight.getSprite(0, 0, 1280, 720);
    setPreferredSize(new Dimension(WIDTH*SCALE,HEIGHT*SCALE));
    initFrame();
}

public void initFrame() {
    frame = new JFrame("Dracula's Castle");
    frame.add(this);
    frame.setResizable(false);
    frame.pack();
    frame.setLocationRelativeTo(null);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);
}

public synchronized void start() {
    thread = new Thread(this);
    isRunning = true;
    thread.start();
}

public synchronized void stop() {

}

public static void main(String args[]) {
    TheGame game = new TheGame();
    game.start();
}

public void tick() {

}


public void render() {    
BufferStrategy bs = this.getBufferStrategy();
if(bs == null) {
    this.createBufferStrategy(3);
    return;
}
Graphics g = background.getGraphics();
g.drawImage(background,0,0,null);
g.dispose();    
}

public void run () {
    long lastTime = System.nanoTime();
    double amountOfTicks = 60.0;
    double ns = 1000000000 / amountOfTicks;
    double delta = 0;
    int frames = 0;
    double timer = System.currentTimeMillis();
    while(isRunning) {
        long now = System.nanoTime();
        delta+= (now - lastTime) / ns; 
        lastTime = now;
        if(delta >= 1) {
            tick();
            render();
            frames++;
            delta--;
}

        if(System.currentTimeMillis() - timer >= 1000){
            System.out.println("FPS:"+ frames);
            frames = 0;
            timer+=1000;
        }       
    }}}

This is the code of the second:

package DracCastle;

import java.awt.image.BufferedImage;
import java.io.IOException;

import javax.imageio.ImageIO;

public class Cenarie{

public Cenarie(String string) {
}

private BufferedImage SkyNight;

public void Skynight (String path) {
    try {
        SkyNight = ImageIO.read(getClass().getResource(path));
    } catch (IOException e) {
        e.printStackTrace();
    }
}

public BufferedImage getSprite(int x,int y,int width,int height) {
    return SkyNight.getSubimage(0, 0, 1280, 720);
}}