Only print errors

We might want to differentiate between "no favicon found" and "got an
error", though.  And metrics would be neat.

go/favicon/favicon.go

var port = flag.Int("p", 8080, "port [8080]")
var cacheSize = flag.Int("s", 10000, "cache size [10000]")
var debug = flag.Bool("debug", false, "Print out debug info")
var faviconCache *lru.Cache
var lock sync.RWMutex
	url := r.URL.Query()["url"][0]
	favicon, err := GetFaviconCached(url)
	if err != nil {
		fmt.Printf("Error: '%s': %s\n", url, err)
		w.WriteHeader(http.StatusNotFound)
		w.Write([]byte(fmt.Sprint(err)))
		return
	if favicon, err := GetCanonicalFavicon(url); err == nil {
		fmt.Println("found favicon.ico")
		return favicon, nil
	} else if *debug {
		fmt.Printf("Error: getting /favicon.ico: %s\n", err)
	}
	resp, err := http.Get(url)
	fmt.Println("get html", resp, err)
	if *debug {
		fmt.Println("get html", resp, err)
	}
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()
	tree, err := html.Parse(resp.Body)
	fmt.Println("parse html", tree, err)
	if *debug {
		fmt.Println("parse html", tree, err)
	}
	if err != nil {
		return "", err
	}
	faviconUrl := fmt.Sprintf("%s://%s/favicon.ico", parsed.Scheme, parsed.Host)
	resp, err := http.Get(faviconUrl)
	fmt.Println("get favicon.ico", resp, err)
	if *debug {
		fmt.Println("get favicon.ico", resp, err)
	}
	if err != nil {
		return "", err
	}
	if err != nil || n == 0 {
		return "", errors.New("can't read /favicon.ico")
	}
	fmt.Println("favicon.ico", resp.Request.URL.String(), faviconUrl)
	if *debug {
		fmt.Println("favicon.ico", resp.Request.URL.String(), faviconUrl)
	}
	return resp.Request.URL.String(), nil
}