go fix'd

pkg/es/errors.go

@@ -18,6 +18,7 @@ package es
 
 import (
 	"fmt"
+	"strings"
 
 	"github.com/elastic/go-elasticsearch/v9/typedapi/types"
 )
@@ -27,14 +28,14 @@ func esErrorString(err error) string {
 
 	switch e := err.(type) {
 	case *types.ElasticsearchError:
-		causes := ""
+		var causes strings.Builder
 
 		for _, cause := range e.ErrorCause.RootCause {
-			causes += fmt.Sprintf("%s\n", *cause.Reason)
+			causes.WriteString(fmt.Sprintf("%s\n", *cause.Reason))
 		}
 
 		if e.ErrorCause.Reason != nil {
-			msg = *e.ErrorCause.Reason + ": " + causes
+			msg = *e.ErrorCause.Reason + ": " + causes.String()
 		} else {
 			msg = fmt.Sprintf("http status %d: ", e.Status)
 		}