fixed file existance checking

main.go

@@ -222,7 +222,7 @@ func downloadSeries(url string, downloadPath string) {
 	downloadCount := 0
 	for i, c := range s.Chapters {
 		chapterPath := fmt.Sprintf("%s/%s", seriesPath, c.Name)
-		if _, err := os.Stat(seriesPath + "/" + c.Name); os.IsNotExist(err) {
+		if _, err := os.Stat(seriesPath + "/" + c.Name + ".cbz"); os.IsNotExist(err) {
 			log.Println("Downloading ", c.Name)
 			downloadChapter(chapterPath, c.Link)
 			//log.Println("Compressing", c.Name)