因errgroup不支持重用，故调整为每次执行时新起

crawler.go

@@ -21,7 +21,6 @@ type Crawler struct {
 	avPath     string
 	outputPath string
 	config     *viper.Viper
-	g          errgroup.Group
 }
 
 func NewCrawler(avPath, outputPath string) *Crawler {
@@ -220,8 +219,9 @@ func (c *Crawler) Handle() error {
 		return err
 	}
 
+	var g errgroup.Group
 	for _, cover := range coverList {
-		c.g.Go(func() error {
+		g.Go(func() error {
 			if err := c.fetchCoverImg(cover); err != nil {
 				return err
 			}
@@ -230,5 +230,5 @@ func (c *Crawler) Handle() error {
 		})
 	}
 
-	return c.g.Wait()
+	return g.Wait()
 }