Using annotated value again in a Django queryset

Question

In this annotation, I'm creating a value ever_error that is 1 if for any unique 'image__image_category__label', 'image__subject', 'image__event' combination and 0 otherwise

d = ImageAcquisitionJob.active_objects.values('image__image_category__label', 'image__subject', 'image__event')\
            .annotate(
                ever_error=(
                    Max( Case(When(has_error=True, then=Value(1)), default=Value(0), output_field=IntegerField()) )
                )
        )

Now, my objective is to make a new annotation that sums up the ever_error attribute for each 'image__image_category__label'

d = d.values('image__image_category__label').annotate(has_error=Sum('ever_error'))

This is not possible however because I get the error: Cannot compute Sum('ever_error'): 'ever_error' is an aggregate

The core of my problem is that I need to use the first annotation again as a regular field but this isn't permitted. Is there a way to save the annotated field so that I can use it again?