NullPointer exception

[Former user]

thank you for your help

2020-07-13 11:16:00,540 [ 449232] ERROR - n.impl.NoSwingUnderWriteAction - AWT events are not allowed inside write action: java.awt.event.InvocationEvent[INVOCATION_DEFAULT,runnable=sun.awt.GlobalCursorManager$NativeUpdater@35030667,notifier=null,catchExceptions=false,when=1594653360348] on sun.awt.windows.WToolkit@38b12b1e java.lang.Throwable: AWT events are not allowed inside write action: java.awt.event.InvocationEvent[INVOCATION_DEFAULT,runnable=sun.awt.GlobalCursorManager$NativeUpdater@35030667,notifier=null,catchExceptions=false,when=1594653360348] on sun.awt.windows.WToolkit@38b12b1e at com.intellij.openapi.diagnostic.Logger.error(Logger.java:146) at com.intellij.openapi.application.impl.NoSwingUnderWriteAction.lambda$watchForEvents$0(NoSwingUnderWriteAction.java:22) at com.intellij.ide.IdeEventQueue.lambda$dispatchEvent$9(IdeEventQueue.java:469) at com.intellij.openapi.application.impl.ApplicationImpl.runIntendedWriteActionOnCurrentThread(ApplicationImpl.java:831) at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:502) 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.pumpEventsForFilter(EventDispatchThread.java:117) at java.desktop/java.awt.WaitDispatchSupport$2.run(WaitDispatchSupport.java:190) at java.desktop/java.awt.WaitDispatchSupport$4.run(WaitDispatchSupport.java:235) at java.desktop/java.awt.WaitDispatchSupport$4.run(WaitDispatchSupport.java:233) at java.base/java.security.AccessController.doPrivileged(Native Method) at java.desktop/java.awt.WaitDispatchSupport.enter(WaitDispatchSupport.java:233) at java.desktop/java.awt.Dialog.show(Dialog.java:1063) at com.intellij.openapi.ui.impl.DialogWrapperPeerImpl$MyDialog.show(DialogWrapperPeerImpl.java:708) at com.intellij.openapi.ui.impl.DialogWrapperPeerImpl.show(DialogWrapperPeerImpl.java:437) at com.intellij.openapi.ui.DialogWrapper.doShow(DialogWrapper.java:1685) at com.intellij.openapi.ui.DialogWrapper.show(DialogWrapper.java:1644) at com.intellij.openapi.ui.messages.MessageDialog.show(MessageDialog.java:176) at com.intellij.ui.messages.MessagesServiceImpl.showMessageDialog(MessagesServiceImpl.java:69) at com.intellij.openapi.ui.Messages.showDialog(Messages.java:246) at com.intellij.openapi.ui.Messages.showDialog(Messages.java:205) at com.intellij.openapi.ui.Messages.showErrorDialog(Messages.java:846) at org.pmesmeur.sketchit.ui.ExceptionDialog.show(ExceptionDialog.java:13) at org.pmesmeur.sketchit.SketchIt.generatePlantUmlDiagramWithExceptionHandling(SketchIt.java:63) at org.pmesmeur.sketchit.SketchIt.generatePlantUmlModel(SketchIt.java:53) at org.pmesmeur.sketchit.SketchIt.actionBody(SketchIt.java:45) at org.pmesmeur.sketchit.SketchIt.access$000(SketchIt.java:12) at org.pmesmeur.sketchit.SketchIt$1.run(SketchIt.java:32) at com.intellij.openapi.application.impl.ApplicationImpl.runWriteAction(ApplicationImpl.java:976) at org.pmesmeur.sketchit.SketchIt.runInsideAnIntellijWriteAction(SketchIt.java:30) at org.pmesmeur.sketchit.SketchIt.actionPerformed(SketchIt.java:24) at com.intellij.openapi.actionSystem.ex.ActionUtil.performActionDumbAware(ActionUtil.java:280) at com.intellij.openapi.actionSystem.impl.ActionMenuItem$ActionTransmitter.lambda$actionPerformed$0(ActionMenuItem.java:296) at com.intellij.openapi.wm.impl.FocusManagerImpl.runOnOwnContext(FocusManagerImpl.java:281) at com.intellij.openapi.wm.impl.IdeFocusManagerImpl.runOnOwnContext(IdeFocusManagerImpl.java:77) at com.intellij.openapi.actionSystem.impl.ActionMenuItem$ActionTransmitter.actionPerformed(ActionMenuItem.java:285) at java.desktop/javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1967) at com.intellij.openapi.actionSystem.impl.ActionMenuItem.lambda$fireActionPerformed$0(ActionMenuItem.java:112) at com.intellij.openapi.application.TransactionGuardImpl.performUserActivity(TransactionGuardImpl.java:94) at com.intellij.openapi.actionSystem.impl.ActionMenuItem.fireActionPerformed(ActionMenuItem.java:112) at com.intellij.ui.plaf.beg.BegMenuItemUI.doClick(BegMenuItemUI.java:517) at com.intellij.ui.plaf.beg.BegMenuItemUI.access$300(BegMenuItemUI.java:36) at com.intellij.ui.plaf.beg.BegMenuItemUI$MyMouseInputHandler.mouseReleased(BegMenuItemUI.java:539) at java.desktop/java.awt.Component.processMouseEvent(Component.java:6650) at java.desktop/javax.swing.JComponent.processMouseEvent(JComponent.java:3345) at java.desktop/java.awt.Component.processEvent(Component.java:6415) at java.desktop/java.awt.Container.processEvent(Container.java:2263) at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:5025) at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2321) at java.desktop/java.awt.Component.dispatchEvent(Component.java:4857) 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:2773) at java.desktop/java.awt.Component.dispatchEvent(Component.java:4857) 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:974) at com.intellij.ide.IdeEventQueue.dispatchMouseEvent(IdeEventQueue.java:912) at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.java:844) at com.intellij.ide.IdeEventQueue.lambda$null$8(IdeEventQueue.java:449) at com.intellij.openapi.progress.impl.CoreProgressManager.computePrioritized(CoreProgressManager.java:741) at com.intellij.ide.IdeEventQueue.lambda$dispatchEvent$9(IdeEventQueue.java:448) at com.intellij.openapi.application.impl.ApplicationImpl.runIntendedWriteActionOnCurrentThread(ApplicationImpl.java:831) at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:502) 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)