Message: Cannot invoke "org.eclipse.jdt.internal.core.JavaElement.close()" because "child" is null

Trace:
```
java.lang.NullPointerException: Cannot invoke "org.eclipse.jdt.internal.core.JavaElement.close()" because "child" is null
at org.eclipse.jdt.internal.core.JavaModelManager.closeChildren(JavaModelManager.java:4107)
at org.eclipse.jdt.internal.core.JavaModelManager.removeInfoAndChildren(JavaModelManager.java:4263)
at org.eclipse.jdt.internal.core.JavaElement.close(JavaElement.java:142)
at org.eclipse.jdt.internal.core.JavaModelManager.closeChildren(JavaModelManager.java:4107)
at org.eclipse.jdt.internal.core.JavaModelManager.removeInfoAndChildren(JavaModelManager.java:4263)
at org.eclipse.jdt.internal.core.JavaElement.close(JavaElement.java:142)
at org.eclipse.jdt.internal.core.JavaModelManager.closeChildren(JavaModelManager.java:4107)
at org.eclipse.jdt.internal.core.JavaModelManager.removeInfoAndChildren(JavaModelManager.java:4263)
at org.eclipse.jdt.internal.core.JavaModelManager.discardPerWorkingCopyInfo(JavaModelManager.java:2056)
at org.eclipse.jdt.internal.core.DiscardWorkingCopyOperation.executeOperation(DiscardWorkingCopyOperation.java:38)
at org.eclipse.jdt.internal.core.JavaModelOperation.run(JavaModelOperation.java:751)
at org.eclipse.jdt.internal.core.JavaModelOperation.runOperation(JavaModelOperation.java:816)
at org.eclipse.jdt.internal.core.CompilationUnit.discardWorkingCopy(CompilationUnit.java:633)
at org.eclipse.jdt.internal.ui.javaeditor.CompilationUnitDocumentProvider.disposeFileInfo(CompilationUnitDocumentProvider.java:1235)
at org.eclipse.ui.editors.text.TextFileDocumentProvider.disconnect(TextFileDocumentProvider.java:662)
at org.eclipse.jdt.internal.ui.javaeditor.CompilationUnitDocumentProvider.disconnect(CompilationUnitDocumentProvider.java:1311)
at org.eclipse.ui.texteditor.AbstractTextEditor.disposeDocumentProvider(AbstractTextEditor.java:4462)
at org.eclipse.ui.texteditor.AbstractDecoratedTextEditor.disposeDocumentProvider(AbstractDecoratedTextEditor.java:1508)
at org.eclipse.ui.texteditor.AbstractTextEditor.dispose(AbstractTextEditor.java:4344)
at org.eclipse.ui.texteditor.AbstractDecoratedTextEditor.dispose(AbstractDecoratedTextEditor.java:408)
at org.eclipse.jdt.internal.ui.javaeditor.JavaEditor.dispose(JavaEditor.java:2679)
at org.eclipse.jdt.internal.ui.javaeditor.CompilationUnitEditor.dispose(CompilationUnitEditor.java:1512)
at org.eclipse.ui.internal.e4.compatibility.CompatibilityPart.invalidate(CompatibilityPart.java:264)
at org.eclipse.ui.internal.e4.compatibility.CompatibilityPart.destroy(CompatibilityPart.java:421)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
at java.base/java.lang.reflect.Method.invoke(Method.java:580)
at org.eclipse.e4.core.internal.di.MethodRequestor.execute(MethodRequestor.java:56)
at org.eclipse.e4.core.internal.di.InjectorImpl.processAnnotated(InjectorImpl.java:977)
at org.eclipse.e4.core.internal.di.InjectorImpl.processAnnotated(InjectorImpl.java:939)
at org.eclipse.e4.core.internal.di.InjectorImpl.uninject(InjectorImpl.java:182)
at org.eclipse.e4.core.internal.di.Requestor.uninject(Requestor.java:177)
at org.eclipse.e4.core.internal.contexts.ContextObjectSupplier$ContextInjectionListener.update(ContextObjectSupplier.java:89)
at org.eclipse.e4.core.internal.contexts.TrackableComputationExt.update(TrackableComputationExt.java:103)
at org.eclipse.e4.core.internal.contexts.EclipseContext.removeListenersTo(EclipseContext.java:487)
at org.eclipse.e4.core.contexts.ContextInjectionFactory.uninject(ContextInjectionFactory.java:185)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeRemoveGui(PartRenderingEngine.java:943)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$4.run(PartRenderingEngine.java:857)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:47)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.removeGui(PartRenderingEngine.java:841)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.subscribeTopicToBeRendered(PartRenderingEngine.java:184)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
at java.base/java.lang.reflect.Method.invoke(Method.java:580)
at org.eclipse.e4.core.internal.di.MethodRequestor.execute(MethodRequestor.java:56)
at org.eclipse.e4.core.di.internal.extensions.EventObjectSupplier$DIEventHandler.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.closePart(StackRenderer.java:1362)
at org.eclipse.e4.ui.workbench.renderers.swt.StackRenderer$3.close(StackRenderer.java:1227)
at org.eclipse.swt.custom.CTabFolder.onMouse(CTabFolder.java:1982)
at org.eclipse.swt.custom.CTabFolder.lambda$0(CTabFolder.java:337)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:91)
at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4321)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1208)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4119)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3707)
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:153)
at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:668)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:339)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:576)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:173)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:178)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:208)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:149)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:115)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:467)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:298)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
at java.base/java.lang.reflect.Method.invoke(Method.java:580)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:670)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:607)
at org.eclipse.equinox.launcher.Main.run(Main.java:1492)
```

Session data:
```
eclipse.buildId=4.35.0.20250306-0811
java.version=21.0.7
java.vendor=Eclipse Adoptium
BootLoader constants: OS=win32, ARCH=x86_64, WS=win32, NL=en_US
Framework arguments: -product org.eclipse.epp.package.java.product -product org.eclipse.epp.package.committers.product
Command-line arguments: -os win32 -ws win32 -arch x86_64 -product org.eclipse.epp.package.java.product -product org.eclipse.epp.package.committers.product -clean
```

Start with JavaModelManager.closeChildren at JavaModelManager.java:4107 and trace the calls through removeInfoAndChildren and DiscardWorkingCopyOperation.executeOperation. Reproduce the crash while closing the Java editor, then verify that the reported null-child failure no longer occurs during CompilationUnit.discardWorkingCopy and editor disposal.

Written by the indexing model from the issue text.