private-link: check for deleted db (#291)

If the database is in a Terminated state, the list of private links
returned will be nil. This adds a check for that nil value and will
result in removing the private link from the local state because the
remote private link has been deleted.

Author: pgier

internal/provider/resource_private_link.go

@@ -144,8 +144,7 @@ func resourcePrivateLinkRead(ctx context.Context, d *schema.ResourceData, meta i
 	if err != nil {
 		return diag.FromErr(err)
 	}
-
-	if string(*privateLinks.ServiceName) == serviceName {
+	if privateLinks != nil && string(*privateLinks.ServiceName) == serviceName {
 		if err := setPrivateLinkData(d, databaseID, datacenterID, serviceName, privateLinks.AllowedPrincipals); err != nil {
 			return diag.FromErr(err)
 		}