make multierr errors private

multierr/multierr.go

@@ -2,21 +2,31 @@ package multierr
 
 import "strings"
 
-type Err []error
+type Err struct {
+	errs []error
+}
 
-func (me Err) Error() string {
+func (me *Err) Error() string {
 	var builder strings.Builder
-	for _, err := range me {
+	for _, err := range me.errs {
 		builder.WriteString("\n")
 		builder.WriteString(err.Error())
 	}
 	return builder.String()
 }
 
-func (me Err) Len() int {
-	return len(me)
+func (me *Err) Errors() []error {
+	return me.errs
+}
+
+func (me *Err) Len() int {
+	return len(me.errs)
 }
 
 func (me *Err) Add(err error) {
-	*me = append(*me, err)
+	me.errs = append(me.errs, err)
+}
+
+func (me *Err) Extend(errs []error) {
+	me.errs = append(me.errs, errs...)
 }