Eclipse doesn't show any problem or a red line, but the app still doesn't run, what should I do?

Question

here is the code:

package application;

import javafx.application.Application;
import javafx.stage.Stage;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.effect.DropShadow;
import javafx.scene.effect.Reflection;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.input.MouseEvent;
import javafx.scene.paint.Color;
import javafx.scene.shape.Line;
import javafx.scene.shape.Rectangle;
import javafx.scene.text.Font;
import javafx.scene.text.Text;

public class Main extends Application {

public void start(Stage primaryStage) {
Group root= new Group();
Scene scene= new Scene(root,600,600,Color.DARKGRAY);

Line line=new Line();
line.setStartX(125);
line.setStartY(103);
line.setEndX(400);
line.setEndY(206);
root.getChildren().add(line);

Rectangle rec= new Rectangle();
rec.setX(400);
rec.setY(400);
rec.setWidth(100);
rec.setHeight(100);
rec.setFill(Color.YELLOW);
rec.setArcHeight(50);
rec.setArcWidth(100);
root.getChildren().add(rec);

Image img= new Image(getClass().getResourceAsStream("bu1.png"));

Button btn= new Button();
btn.setGraphic(new ImageView(img));
btn.setLayoutX(250);
btn.setLayoutY(400);

Label lbl=new Label("Rotation angle: ");

lbl.setLayoutX(250);
lbl.setLayoutY(375);

root.getChildren().addAll(btn,lbl);

DropShadow shadow= new DropShadow();
btn.addEventHandler(MouseEvent.MOUSE_ENTERED,
(MouseEvent e)->{
btn.setEffect(shadow);
});
btn.addEventHandler(MouseEvent.MOUSE_EXITED,
(MouseEvent e)->{
btn.setEffect(null);
});

Text txt=new Text(120,150,"Welcome to JavaFX");
Font fnt=new Font("century gothic",30);
txt.setFont(fnt);
txt.setFill(Color.YELLOW);
txt.setRotate(20);
root.getChildren().add(txt);

Answer 1

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Answer 2

when I click on run , console shows this
Exception in Application start method
java.lang.reflect.InvocationTargetException
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:464)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:363)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at java.base/sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:1051)
Caused by: java.lang.RuntimeException: Exception in Application start method
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:900)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:195)
at java.base/java.lang.Thread.run(Thread.java:832)
Caused by: java.lang.NullPointerException: Input stream must not be null
at javafx.graphics/javafx.scene.image.Image.validateInputStream(Image.java:1135)
at javafx.graphics/javafx.scene.image.Image.<init>(Image.java:702)
at application.Main.start(Main.java:46)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:846)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:455)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$1