refactor: optimize file content encoding in NewAttachmentFromFileContent

client/create.go

@@ -3,6 +3,7 @@ package client
 import (
 	"bytes"
 	"encoding/json"
+	"errors"
 	"net/http"
 	"time"
 )
@@ -12,6 +13,11 @@ type EmailCreateResponse struct {
 	CreatedAt time.Time `json:"created_at"`
 }
 
+type ErrorResponse struct {
+	Message string `json:"message"`
+	Error   string `json:"error"`
+}
+
 func (client *Client) SendEmail(request *EmailRequest) (*EmailCreateResponse, error) {
 	jsonData, _ := json.Marshal(request)
 
@@ -30,6 +36,15 @@ func (client *Client) SendEmail(request *EmailRequest) (*EmailCreateResponse, er
 		return nil, err
 	}
 
+	if resp.StatusCode != http.StatusOK {
+		response, err := readResponseBody[Response[ErrorResponse]](resp)
+		if err != nil {
+			return nil, err
+		}
+
+		return nil, errors.New(response.Payload.Message)
+	}
+
 	response, err := readResponseBody[Response[EmailCreateResponse]](resp)
 	if err != nil {
 		return nil, err