Error launching .JAR program

Hi everyone here. I really hope all of you have a good day.

I used to launch certain GIS programs in .JAR format with no issue, when I used Trisquel with MATE.

But with my last installation, using Trisquel 12 with KDE, I cannot lunch any of them. I tried installing several versions of the JRE. In the system I have installed:

- default-jre

- openjdk-8-jre

- openjdk-11-jre

- openjdk-21-jre

But when I try to launch the program from the CLI, I receive this message:

java -jar gpsprune_20.jar
Exception in thread "main" java.lang.NullPointerException: Cannot invoke "String.startsWith(String)" because "platName" is null
at java.desktop/sun.awt.X11FontManager.getFileNameFromPlatformName(X11FontManager.java:161)
at java.desktop/sun.font.SunFontManager.initCompositeFonts(SunFontManager.java:3102)
at java.desktop/sun.font.SunFontManager$2.run(SunFontManager.java:445)
at java.desktop/sun.font.SunFontManager$2.run(SunFontManager.java:309)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:319)
at java.desktop/sun.font.SunFontManager.(SunFontManager.java:309)
at java.desktop/sun.awt.FcFontManager.(FcFontManager.java:35)
at java.desktop/sun.awt.X11FontManager.(X11FontManager.java:55)
at java.desktop/sun.font.PlatformFontInfo.createFontManager(PlatformFontInfo.java:37)
at java.desktop/sun.font.FontManagerFactory.getInstance(FontManagerFactory.java:51)
at java.desktop/sun.font.SunFontManager.getInstance(SunFontManager.java:242)
at java.desktop/sun.font.FontDesignMetrics.getMetrics(FontDesignMetrics.java:260)
at java.desktop/sun.swing.SwingUtilities2.getFontMetrics(SwingUtilities2.java:1242)
at java.desktop/javax.swing.JComponent.getFontMetrics(JComponent.java:1700)
at java.desktop/javax.swing.plaf.basic.BasicLabelUI.getPreferredSize(BasicLabelUI.java:251)
at java.desktop/javax.swing.JComponent.getPreferredSize(JComponent.java:1734)
at java.desktop/javax.swing.plaf.basic.BasicComboBoxRenderer.getPreferredSize(BasicComboBoxRenderer.java:89)
at java.desktop/javax.swing.plaf.basic.BasicListUI.updateLayoutState(BasicListUI.java:1446)
at java.desktop/javax.swing.plaf.basic.BasicListUI.maybeUpdateLayoutState(BasicListUI.java:1394)
at java.desktop/javax.swing.plaf.basic.BasicListUI$Handler.valueChanged(BasicListUI.java:2815)
at java.desktop/javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:231)
at java.desktop/javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:206)
at java.desktop/javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:258)
at java.desktop/javax.swing.DefaultListSelectionModel.changeSelection(DefaultListSelectionModel.java:459)
at java.desktop/javax.swing.DefaultListSelectionModel.changeSelection(DefaultListSelectionModel.java:469)
at java.desktop/javax.swing.DefaultListSelectionModel.setSelectionInterval(DefaultListSelectionModel.java:513)
at java.desktop/javax.swing.JList.setSelectedIndex(JList.java:2232)
at java.desktop/javax.swing.plaf.basic.BasicComboPopup.setListSelection(BasicComboPopup.java:1281)
at java.desktop/javax.swing.plaf.basic.BasicComboPopup$Handler.itemStateChanged(BasicComboPopup.java:1097)
at java.desktop/javax.swing.JComboBox.fireItemStateChanged(JComboBox.java:1257)
at java.desktop/javax.swing.JComboBox.selectedItemChanged(JComboBox.java:1318)
at java.desktop/javax.swing.JComboBox.contentsChanged(JComboBox.java:1365)
at java.desktop/javax.swing.AbstractListModel.fireContentsChanged(AbstractListModel.java:127)
at java.desktop/javax.swing.DefaultComboBoxModel.setSelectedItem(DefaultComboBoxModel.java:94)
at java.desktop/javax.swing.DefaultComboBoxModel.addElement(DefaultComboBoxModel.java:132)
at java.desktop/javax.swing.JComboBox.addItem(JComboBox.java:746)
at tim.prune.gui.DetailsDisplay.(Unknown Source)
at tim.prune.GpsPrune.launch(Unknown Source)
at tim.prune.GpsPrune.main(Unknown Source)


And the same happens with other versions of the program, which I used in the past with no problem, all of them in .JAR format.

I am not certain if the issue is due to the JRE or if it is something about the guts of the .JAR file itself.

I will appreciate immensely your kind help.

Sending to all of you my best wishes.