fix bug

pkg/common/db/rocks_cache/rocks_cache.go

@@ -8,6 +8,7 @@ import (
 	"Open_IM/pkg/utils"
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"time"
 )
@@ -323,6 +324,9 @@ func GetJoinedSuperGroupListFromCache(userID string) ([]string, error) {
 		if err != nil {
 			return "", utils.Wrap(err, "")
 		}
+		if len(userToSuperGroup.GroupIDList) == 0 {
+			return "", errors.New("GroupIDList == 0")
+		}
 		bytes, err := json.Marshal(userToSuperGroup.GroupIDList)
 		return string(bytes), utils.Wrap(err, "")
 	}