App crashes when resetting the preview settings

[angns9]

To reproduce the issue, simply click the reset button that appears in the preview settings dialog.

Version: ver 1.0.9
OS: Windows
com.ray3k.gdxparticleeditor.lwjgl3.Lwjgl3Launcher: Error while running application
java.lang.RuntimeException: Actor: TextButton: Reset
	at com.badlogic.gdx.scenes.scene2d.Actor.notify(Actor.java:192)
	at com.badlogic.gdx.scenes.scene2d.Actor.fire(Actor.java:152)
	at com.badlogic.gdx.scenes.scene2d.ui.Button.setChecked(Button.java:125)
	at com.badlogic.gdx.scenes.scene2d.ui.Button$1.clicked(Button.java:93)
	at com.badlogic.gdx.scenes.scene2d.utils.ClickListener.touchUp(ClickListener.java:88)
	at com.badlogic.gdx.scenes.scene2d.InputListener.handle(InputListener.java:71)
	at com.badlogic.gdx.scenes.scene2d.Stage.touchUp(Stage.java:354)
	at com.badlogic.gdx.InputEventQueue.drain(InputEventQueue.java:70)
	at com.badlogic.gdx.backends.lwjgl3.DefaultLwjgl3Input.update(DefaultLwjgl3Input.java:229)
	at com.badlogic.gdx.backends.lwjgl3.Lwjgl3Window.update(Lwjgl3Window.java:378)
	at com.badlogic.gdx.backends.lwjgl3.Lwjgl3Application.loop(Lwjgl3Application.java:193)
	at com.badlogic.gdx.backends.lwjgl3.Lwjgl3Application.<init>(Lwjgl3Application.java:167)
	at com.ray3k.gdxparticleeditor.lwjgl3.Lwjgl3Launcher.createApplication(Lwjgl3Launcher.java:20)
	at com.ray3k.gdxparticleeditor.lwjgl3.Lwjgl3Launcher.main(Lwjgl3Launcher.java:12)
Caused by: java.lang.NullPointerException: Cannot invoke "com.badlogic.gdx.scenes.scene2d.ui.Image.setColor(com.badlogic.gdx.graphics.Color)" because "com.ray3k.gdxparticleeditor.widgets.panels.PreviewPanel.previewBackgroundImage" is null
	at com.ray3k.gdxparticleeditor.widgets.poptables.PopPreviewSettings.lambda$new$26(PopPreviewSettings.java:701)
	at com.ray3k.gdxparticleeditor.Listeners$2.changed(Listeners.java:89)
	at com.badlogic.gdx.scenes.scene2d.utils.ChangeListener.handle(ChangeListener.java:28)
	at com.badlogic.gdx.scenes.scene2d.Actor.notify(Actor.java:188)
	... 13 more