How might I fix this problem - can't find any error in my code and the program seems to run without any problem but this window keeps popping up! Thank you for any guidance.
Exception in thread "AWT-EventQueue-0" java.lang.IllegalStateException: Not on FX application thread; currentThread = AWT-EventQueue-0 at com.sun.javafx.tk.Toolkit.checkFxUserThread(Toolkit.java:236) at com.sun.javafx.tk.quantum.QuantumToolkit.checkFxUserThread(QuantumToolkit.java:423) at javafx.stage.Window.setShowing(Window.java:921) at javafx.stage.Window.hide(Window.java:947) at greenfoot.gui.GreenfootInspectorManager.removeAllInspectors(GreenfootInspectorManager.java:148) at greenfoot.gui.GreenfootFrame.worldRemoved(GreenfootFrame.java:1315) at greenfoot.core.WorldHandler.fireWorldRemovedEvent(WorldHandler.java:866) at greenfoot.core.WorldHandler.lambda$discardWorld$0(WorldHandler.java:591) at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311) at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756) at java.awt.EventQueue.access$500(EventQueue.java:97) at java.awt.EventQueue$3.run(EventQueue.java:709) at java.awt.EventQueue$3.run(EventQueue.java:703) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76) at java.awt.EventQueue.dispatchEvent(EventQueue.java:726) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93) at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
