improved error messages

api/fiscal.go

@@ -18,6 +18,7 @@ func (c *Client) executeRequest(ctx context.Context, request FiscalRequest, resp
 	resp, err := c.resty.R().
 		SetContext(ctx).
 		SetHeader("Authorization", c.token).
+		SetHeader("Content-Type", "application/json").
 		SetBody(reqJson).
 		Post(c.apiBaseURL + c.fiscalEndpoint)
 
@@ -25,21 +26,17 @@ func (c *Client) executeRequest(ctx context.Context, request FiscalRequest, resp
 		return fmt.Errorf("request failed: %w", err)
 	}
 
-	if resp.IsError() {
-		return fmt.Errorf("api error: %v", resp.Error())
-	}
-
-	if resp.StatusCode() != 200 {
-		return fmt.Errorf("unexpected status code: %d", resp.StatusCode())
-	}
-
 	body, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return fmt.Errorf("failed to read response: %w", err)
 	}
 
+	if resp.StatusCode() != 200 {
+		return fmt.Errorf("api error (status %d): %s", resp.StatusCode(), string(body))
+	}
+
 	if err := json.Unmarshal(body, response); err != nil {
-		return fmt.Errorf("failed to unmarshal response: %w", err)
+		return fmt.Errorf("failed to unmarshal response: %w, body: %s", err, string(body))
 	}
 
 	return nil