Attempting to fetch nonexisting /sitemap.xml.gz results in "gzip: invalid header"

[WGH-]

package main

import (
	"log"
	"net/http"

	"github.com/gocolly/colly/v2"
)

func main() {
	// we have to disable Accept-Encoding: gzip,
	// because the remote server might send compressed
	// 404 page, avoiding the bug
	tr := &http.Transport{
		DisableCompression: true,
	}

	c := colly.NewCollector()
	c.WithTransport(tr)

	c.OnError(func(resp *colly.Response, err error) {
		log.Printf("err=%v", err)
	})

	c.Visit("https://example.org/sitemap.xml.gz")
}

Results in:

2023/01/05 22:30:27 err=gzip: invalid header