You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: get.go
    path of file: ./repos/ddns-updater/internal/provider/providers/ionos
    
    the code of the file until where you have to start completion: package ionos

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"path/filepath"
	"strings"

	"github.com/qdm12/ddns-updater/internal/provider/er
    
func decodeErrorMessage(body io.Reader) (message string) {
	b, err := io.ReadAll(body)
	if err != nil {
		return fmt.Sprintf("failed reading response body: %s", err)
	}

	if len(b) == 0 {
		return ""
	}

	var data []struct {
		Code    string `json:"code"`
		Message string `json:"message"`
	}
	err = json.Unmarshal(b, &data)
	if err != nil {
		return "failed decoding the following: " + string(b)
	}
	if len(data) == 0 {
		return "no message found"
	}

	messages := make([]string, len(data))
	for i, object := range data {
		if object.Message != "" {
			messages[i] = object.Message
			continue
		}
		messages[i] = fmt.Sprintf("code %q", object.Code)
	}
	return strings.Join(messages, "; ")
}