NullPointerException when closing multiple Papyrus editors

Way to reproduce :

open multiple Papyrus editors
Close all editors

java.lang.NullPointerException: Cannot invoke "org.eclipse.gmf.runtime.diagram.ui.editparts.DiagramEditPart.getParent()" because "diagramEP" is null at org.eclipse.papyrus.infra.gmfdiag.common.SynchronizableGmfDiagramEditor.dispose(SynchronizableGmfDiagramEditor.java:113) at org.eclipse.papyrus.uml.diagram.common.part.UmlGmfDiagramEditor.dispose(UmlGmfDiagramEditor.java:217) at org.eclipse.papyrus.uml.diagram.statemachine.part.UMLDiagramEditor.dispose(UMLDiagramEditor.java:335) at org.eclipse.papyrus.uml.diagram.statemachine.UmlStateMachineDiagramForMultiEditor.dispose(UmlStateMachineDiagramForMultiEditor.java:108) at org.eclipse.papyrus.infra.core.sasheditor.internal.EditorPart$4.run(EditorPart.java:468) at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:47) at org.eclipse.papyrus.infra.core.sasheditor.internal.EditorPart.disposeEditorPart(EditorPart.java:463) at org.eclipse.papyrus.infra.core.sasheditor.internal.EditorPart$2.widgetDisposed(EditorPart.java:123) at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:140) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:91) at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4285) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1160) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1184) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1165) at org.eclipse.swt.widgets.Widget.release(Widget.java:877) at org.eclipse.swt.widgets.Composite.releaseChildren(Composite.java:929) at org.eclipse.swt.widgets.Widget.release(Widget.java:884) at org.eclipse.swt.widgets.Widget.dispose(Widget.java:466) at org.eclipse.papyrus.infra.core.sasheditor.internal.SashWindowsContainer.dispose(SashWindowsContainer.java:310) at org.eclipse.papyrus.infra.core.sasheditor.internal.SashWindowsContainer$1.widgetDisposed(SashWindowsContainer.java:157) at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:140) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:91) at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4285) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1160) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1184) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1165) at org.eclipse.swt.widgets.Widget.release(Widget.java:877) at org.eclipse.swt.widgets.Composite.releaseChildren(Composite.java:929) at org.eclipse.swt.widgets.Widget.release(Widget.java:884) at org.eclipse.swt.widgets.Widget.dispose(Widget.java:466) at org.eclipse.e4.ui.workbench.renderers.swt.SWTPartRenderer.disposeWidget(SWTPartRenderer.java:183) at org.eclipse.e4.ui.workbench.renderers.swt.ContributedPartRenderer.disposeWidget(ContributedPartRenderer.java:282) at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeRemoveGui(PartRenderingEngine.java:934) at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine4.run(PartRenderingEngine.java:857) at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:47) at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.removeGui(PartRenderingEngine.java:841) at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.subscribeTopicToBeRendered(PartRenderingEngine.java:184) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:568) at org.eclipse.e4.core.internal.di.MethodRequestor.execute(MethodRequestor.java:58) at org.eclipse.e4.core.di.internal.extensions.EventObjectSupplierDIEventHandler.handleEvent(EventObjectSupplier.java:92) at org.eclipse.equinox.internal.event.EventHandlerWrapper.handleEvent(EventHandlerWrapper.java:206) at org.eclipse.equinox.internal.event.EventHandlerTracker.dispatchEvent(EventHandlerTracker.java:201) at org.eclipse.equinox.internal.event.EventHandlerTracker.dispatchEvent(EventHandlerTracker.java:1) at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230) at org.eclipse.osgi.framework.eventmgr.ListenerQueue.dispatchEventSynchronous(ListenerQueue.java:151) at org.eclipse.equinox.internal.event.EventAdminImpl.dispatchEvent(EventAdminImpl.java:131) at org.eclipse.equinox.internal.event.EventAdminImpl.sendEvent(EventAdminImpl.java:73) at org.eclipse.equinox.internal.event.EventComponent.sendEvent(EventComponent.java:44) at org.eclipse.e4.ui.services.internal.events.EventBroker.send(EventBroker.java:55) at org.eclipse.e4.ui.internal.workbench.UIEventPublisher.notifyChanged(UIEventPublisher.java:60) at org.eclipse.emf.common.notify.impl.BasicNotifierImpl.eNotify(BasicNotifierImpl.java:424) at org.eclipse.e4.ui.model.application.ui.impl.UIElementImpl.setToBeRendered(UIElementImpl.java:316) at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.hidePart(PartServiceImpl.java:1411) at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.hidePart(PartServiceImpl.java:1341) at org.eclipse.e4.ui.workbench.renderers.swt.StackRenderer.closeSiblingParts(StackRenderer.java:1730) at org.eclipse.e4.ui.workbench.renderers.swt.StackRenderer.closeSiblingParts(StackRenderer.java:1687) at org.eclipse.e4.ui.workbench.renderers.swt.StackRenderer.lambda$38(StackRenderer.java:1521) at org.eclipse.swt.events.SelectionListener$1.widgetSelected(SelectionListener.java:84) at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:265) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:91) at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4285) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1160) at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4083) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3673) at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1151) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:339) at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1042) at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:152) at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:639) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:339) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:546) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:173) at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:152) at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:208) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:143) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:109) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:439) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:271) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:568) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:668) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:605) at org.eclipse.equinox.launcher.Main.run(Main.java:1481) at org.eclipse.equinox.launcher.Main.main(Main.java:1454)