fix linter errors, enhance error handling, rename Id to ID in tpls

fetch.go

@@ -52,7 +52,7 @@ func NewFetcher(conf *Config) (*Fetcher, error) {
 }
 
 func (f *Fetcher) Get(uri string) (io.ReadCloser, error) {
-	req, err := http.NewRequest("GET", uri, nil)
+	req, err := http.NewRequest(http.MethodGet, uri, nil)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create a new HTTP request obj: %w", err)
 	}
@@ -61,10 +61,12 @@ func (f *Fetcher) Get(uri string) (io.ReadCloser, error) {
 
 	if len(f.Cookies) > 0 {
 		uriobj, _ := url.Parse(Baseuri)
+
 		slog.Debug("have cookies, sending them",
 			"sample-cookie-name", f.Cookies[0].Name,
 			"sample-cookie-expire", f.Cookies[0].Expires,
 		)
+
 		f.Client.Jar.SetCookies(uriobj, f.Cookies)
 	}
 
@@ -73,7 +75,7 @@ func (f *Fetcher) Get(uri string) (io.ReadCloser, error) {
 		return nil, fmt.Errorf("failed to initiate HTTP request to %s: %w", uri, err)
 	}
 
-	if res.StatusCode != 200 {
+	if res.StatusCode != http.StatusOK {
 		return nil, errors.New("could not get page via HTTP")
 	}
 
@@ -86,12 +88,15 @@ func (f *Fetcher) Get(uri string) (io.ReadCloser, error) {
 // fetch an image
 func (f *Fetcher) Getimage(uri string) (io.ReadCloser, error) {
 	slog.Debug("fetching ad image", "uri", uri)
+
 	body, err := f.Get(uri)
 	if err != nil {
 		if f.Config.IgnoreErrors {
 			slog.Info("Failed to download image, error ignored", "error", err.Error())
+
 			return nil, nil
 		}
+
 		return nil, err
 	}