chore(errors): review all errors in codebase

internal/wireguard/ipv6.go

@@ -1,27 +1,21 @@
 package wireguard
 
 import (
-	"errors"
 	"fmt"
 
 	"github.com/qdm12/gluetun/internal/netlink"
 )
 
-var (
-	errLinkList  = errors.New("cannot list links")
-	errRouteList = errors.New("cannot list routes")
-)
-
 func (w *Wireguard) isIPv6Supported() (supported bool, err error) {
 	links, err := w.netlink.LinkList()
 	if err != nil {
-		return false, fmt.Errorf("%w: %s", errLinkList, err)
+		return false, fmt.Errorf("cannot list links: %w", err)
 	}
 
 	for _, link := range links {
 		routes, err := w.netlink.RouteList(link, netlink.FAMILY_V6)
 		if err != nil {
-			return false, fmt.Errorf("%w: %s", errRouteList, err)
+			return false, fmt.Errorf("cannot list routes: %w", err)
 		}
 
 		if len(routes) > 0 {