Use errors.Join instead of copied version

errors.go

@@ -1,43 +0,0 @@
-package ctrld
-
-// TODO(cuonglm): use stdlib once we bump minimum version to 1.20
-
-func joinErrors(errs ...error) error {
-	n := 0
-	for _, err := range errs {
-		if err != nil {
-			n++
-		}
-	}
-	if n == 0 {
-		return nil
-	}
-	e := &joinError{
-		errs: make([]error, 0, n),
-	}
-	for _, err := range errs {
-		if err != nil {
-			e.errs = append(e.errs, err)
-		}
-	}
-	return e
-}
-
-type joinError struct {
-	errs []error
-}
-
-func (e *joinError) Error() string {
-	var b []byte
-	for i, err := range e.errs {
-		if i > 0 {
-			b = append(b, '\n')
-		}
-		b = append(b, err.Error()...)
-	}
-	return string(b)
-}
-
-func (e *joinError) Unwrap() []error {
-	return e.errs
-}

resolver.go

@@ -93,7 +93,7 @@ func (o *osResolver) Resolve(ctx context.Context, msg *dns.Msg) (*dns.Msg, error
 		errs = append(errs, res.err)
 	}
 
-	return nil, joinErrors(errs...)
+	return nil, errors.Join(errs...)
 }
 
 func newDialer(dnsAddress string) *net.Dialer {