The JDK API for opening a browser is pretty stupid, an issue that also IDEA hat for a long time. The AWT API simply fails on Linux:
java.lang.UnsupportedOperationException: The BROWSE action is not supported on the current platform!
at java.desktop/java.awt.Desktop.checkActionSupport(Desktop.java:380)
at java.desktop/java.awt.Desktop.browse(Desktop.java:524)
at no.hvl.tk.visual.debugger.debugging.visualization.WebSocketDebuggingVisualizer.launchUIInBrowser(WebSocketDebuggingVisualizer.java:64)
at no.hvl.tk.visual.debugger.debugging.visualization.WebSocketDebuggingVisualizer.lambda$debuggingActivated$1(WebSocketDebuggingVisualizer.java:56)
at java.desktop/javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1967)
at java.desktop/javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2308)
at java.desktop/javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:405)
at java.desktop/javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:262)
at java.desktop/javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:270)
at java.desktop/java.awt.Component.processMouseEvent(Component.java:6652)
at java.desktop/javax.swing.JComponent.processMouseEvent(JComponent.java:3345)
at java.desktop/java.awt.Component.processEvent(Component.java:6417)
at java.desktop/java.awt.Container.processEvent(Container.java:2263)
at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:5027)
at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2321)
at java.desktop/java.awt.Component.dispatchEvent(Component.java:4859)
at java.desktop/java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4918)
at java.desktop/java.awt.LightweightDispatcher.processMouseEvent(Container.java:4547)
at java.desktop/java.awt.LightweightDispatcher.dispatchEvent(Container.java:4488)
at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2307)
at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2784)
at java.desktop/java.awt.Component.dispatchEvent(Component.java:4859)
at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:778)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:727)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:95)
at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:751)
at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:749)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:748)
at com.intellij.ide.IdeEventQueue.defaultDispatchEvent(IdeEventQueue.java:885)
at com.intellij.ide.IdeEventQueue.dispatchMouseEvent(IdeEventQueue.java:814)
at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.java:751)
at com.intellij.ide.IdeEventQueue.lambda$dispatchEvent$6(IdeEventQueue.java:441)
at com.intellij.openapi.progress.impl.CoreProgressManager.computePrioritized(CoreProgressManager.java:825)
at com.intellij.ide.IdeEventQueue.lambda$dispatchEvent$7(IdeEventQueue.java:440)
at com.intellij.openapi.application.impl.ApplicationImpl.runIntendedWriteActionOnCurrentThread(ApplicationImpl.java:794)
at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:492)
at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
Tho I would not mind a graceful note / MsgBox with a link, that might also work.