fixed panic if no Accept-Lang header os set

main.go

@@ -624,7 +624,12 @@ func getMatchChat(c *gin.Context) {
 		c.Status(http.StatusBadRequest)
 		return
 	}
-	lang, _ := tag[0].Base()
+	var lang string
+	if len(tag) > 0 {
+		lang, _ = tag[0].Base()
+	} else {
+		lang = "en"
+	}
 	log.Debugf("[GMC] Got header %s, selected %s from %v (w: %v)", c.GetHeader("Accept-Language"), lang, tag, weights)
 
 	var translate bool