[GREENFOOT-452] Exception while deleting frame

Full trace:

{noformat} parentCanvas shouldn't be null; call stack: bluej.stride.framedjava.frames.VarFrame.isField(VarFrame.java:282) bluej.stride.framedjava.frames.VarFrame.getContextOperations(VarFrame.java:311) bluej.editor.stride.FrameSelection.getMenuItems(FrameSelection.java:247) bluej.stride.generic.FrameCursor.getMenuItems(FrameCursor.java:798) bluej.editor.stride.CursorOrSlot.getMenuItems(CursorOrSlot.java:91) bluej.editor.stride.FrameEditorTab.lambda$initialiseFX$430(FrameEditorTab.java:336) bluej.utility.javafx.JavaFXUtil.lambda$addChangeListener$955(JavaFXUtil.java:975) com.sun.javafx.binding.ExpressionHelper$SingleChange.fireValueChangedEvent(ExpressionHelper.java:182) com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81) javafx.beans.property.ObjectPropertyBase.fireValueChangedEvent(ObjectPropertyBase.java:105) javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:112) javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:146) bluej.editor.stride.FrameEditorTab.lambda$setupFocusable$515(FrameEditorTab.java:1936) com.sun.javafx.binding.ExpressionHelper$Generic.fireValueChangedEvent(ExpressionHelper.java:361) com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81) javafx.beans.property.ReadOnlyBooleanPropertyBase.fireValueChangedEvent(ReadOnlyBooleanPropertyBase.java:72) javafx.scene.Node$FocusedProperty.notifyListeners(Node.java:7718) javafx.scene.Scene$13.invalidated(Scene.java:2080) javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:111) javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:146) javafx.scene.Scene$KeyHandler.setFocusOwner(Scene.java:3924) javafx.scene.Scene$KeyHandler.requestFocus(Scene.java:3971) javafx.scene.Scene$KeyHandler.access$1900(Scene.java:3910) javafx.scene.Scene.requestFocus(Scene.java:2044) javafx.scene.Node.requestFocus(Node.java:7879) bluej.stride.generic.FrameCursor.requestFocus(FrameCursor.java:752) bluej.stride.operations.DeleteFrameOperation.execute(DeleteFrameOperation.java:68) bluej.stride.operations.FrameOperation.activate(FrameOperation.java:82) bluej.stride.operations.FrameOperation.activate(FrameOperation.java:74) bluej.stride.operations.FrameOperation.lambda$null$400(FrameOperation.java:111) com.sun.javafx.application.PlatformImpl.lambda$null$174(PlatformImpl.java:295) java.security.AccessController.doPrivileged(Native Method) com.sun.javafx.application.PlatformImpl.lambda$runLater$175(PlatformImpl.java:294) com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95) com.sun.glass.ui.win.WinApplication._runLoop(Native Method) com.sun.glass.ui.win.WinApplication.lambda$null$149(WinApplication.java:191) java.lang.Thread.run(Thread.java:745) {noformat}

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Issue metadata

• Issue type: Bug
• Priority: Low
• Fix versions: 3.0.3