Unless an error of law as defined in § 2.2-4027 appears, the court shall dismiss the review action or affirm the agency regulation or decision. Otherwise, it may compel agency action unlawfully and arbitrarily withheld or unreasonably delayed except that the court shall not itself undertake to supply agency action committed by the basic law to the agency. Where a regulation or case decision is found by the court not to be in accordance with law under § 2.2-4027, the court shall suspend or set it aside and remand the matter to the agency for further proceedings, if any, as the court may permit or direct in accordance with law.