Description Samantha Chan 2011-08-05 15:28:36 EDT

I am getting NPE when trying to dispose a customized OutlinePage.  The reason is in the deregister method from LinkWithEditorOutlineContribution:

	@Override
	public void deregister(OutlinePage outlinePage) {
		super.deregister(outlinePage);
		OutlineWithEditorLinker outlineWithEditorLinker = page2linker.remove(outlinePage);
		outlineWithEditorLinker.deactivate();
		getPreferenceStoreAccess().getPreferenceStore().removePropertyChangeListener(outlineWithEditorLinker);
	}

In here, page2linker.remove(...) may return null.  You then call outlineWithEditorLinker.deactivate() without checking its return value... and resulted in the NPE.