OCPBUGS-27737: aws-edge-zones: preventing errors when discovering phase

AWS Wavelength Zones have been introduced as part of edge-zones in 4.15.
The function used to discover the valid edge zones in the region is
prematurely returning errors when the region haven't available any of
Local Zones or Wavelength Zones, which could cause issues in regions
which support only one edge zone type.

https://issues.redhat.com//browse/OCPBUGS-27737

Author: mtulio

pkg/asset/installconfig/aws/availabilityzones.go

@@ -71,7 +71,7 @@ func describeAvailabilityZones(ctx context.Context, session *session.Session, re
 
 // filterZonesByType retrieves a list of zones by a given ZoneType attribute within the region.
 // ZoneType can be availability-zone, local-zone or wavelength-zone.
-func filterZonesByType(ctx context.Context, session *session.Session, region string, zoneType string) ([]string, error) {
+func filterZonesByType(ctx context.Context, session *session.Session, region, zoneType string) ([]string, error) {
 	azs, err := describeAvailabilityZones(ctx, session, region, []string{})
 	if err != nil {
 		return nil, fmt.Errorf("fetching %s: %w", zoneType, err)
@@ -83,16 +83,19 @@ func filterZonesByType(ctx context.Context, session *session.Session, region str
 		}
 	}
 
-	if len(zones) == 0 {
-		return nil, fmt.Errorf("no zones with type %s in %s", zoneType, region)
-	}
-
 	return zones, nil
 }
 
 // availabilityZones retrieves a list of zones type 'availability-zone' in the region.
 func availabilityZones(ctx context.Context, session *session.Session, region string) ([]string, error) {
-	return filterZonesByType(ctx, session, region, typesaws.AvailabilityZoneType)
+	zones, err := filterZonesByType(ctx, session, region, typesaws.AvailabilityZoneType)
+	if err != nil {
+		return nil, err
+	}
+	if len(zones) == 0 {
+		return nil, fmt.Errorf("no zones with type availability-zone in %s", region)
+	}
+	return zones, nil
 }
 
 // edgeZones retrieves a list of zones type 'local-zone' and 'wavelength-zone' in the region.
@@ -110,6 +113,10 @@ func edgeZones(ctx context.Context, session *session.Session, region string) ([]
 	edgeZones = append(edgeZones, localZones...)
 	edgeZones = append(edgeZones, wavelengthZones...)
 
+	if len(edgeZones) == 0 {
+		return nil, fmt.Errorf("unable to find zone types with local-zone or wavelength-zone in the region %s", region)
+	}
+
 	return edgeZones, nil
 }