handle http errors better

client.go

@@ -36,7 +36,6 @@ func NewClient(baseURL, salt string) *Client {
 }
 
 func (c *Client) CalculateHash(url string) string {
-	// The hash should be calculated by appending the salt to the URL with a colon separator.
 	data := url + ":" + c.Salt
 	hash := md5.Sum([]byte(data))
 	return hex.EncodeToString(hash[:])
@@ -71,12 +70,15 @@ func (c *Client) Scrape(ctx context.Context, url, selector string) (ScrapeRespon
 	}
 	defer resp.Body.Close()
 
+	if resp.StatusCode != http.StatusOK {
+		return ScrapeResponse{}, fmt.Errorf("received non-OK response: %s", resp.Status)
+	}
+
 	body, err := ioutil.ReadAll(resp.Body)
 	if err != nil {
 		return ScrapeResponse{}, fmt.Errorf("failed to read response body: %v", err)
 	}
 
-	// Since the response is HTML, we don't need to unmarshal JSON.
 	content := string(body)
 
 	return ScrapeResponse{