If a court denies habeas relief on procedural grounds without reaching the underlying constitutional claims, should the court issue a certificate of appeal?

If a court denies habeas relief on procedural grounds without reaching the underlying constitutional claims, the court should issue a certificate of appealability "if jurists of reason would find it debatable whether the petition states a valid claim of the denial of a constitutional right and that jurists of reason would find it debatable whether the district court was correct in its procedural ruling." Slack v. McDaniel, 529 U.S. 473, 484 (2000). "Where a plain procedural bar is present and the district court is correct to invoke it to dispose of the case, a reasonable jurist could not conclude either that the district court erred in dismissing the petition or that the petitioner should be allowed to proceed further." Id.