fix: listLeaseExpiredCmd doesn't ignore possibly empty value of task …

…in lua script

internal/rdb/rdb.go

@@ -1284,7 +1284,10 @@ local res = {}
 local ids = redis.call("ZRANGEBYSCORE", KEYS[1], "-inf", ARGV[1])
 for _, id in ipairs(ids) do
 	local key = ARGV[2] .. id
-	table.insert(res, redis.call("HGET", key, "msg"))
+	local v = redis.call("HGET", key, "msg")
+	if v then
+		table.insert(res, v)
+	end
 end
 return res
 `)
@@ -1305,9 +1308,6 @@ func (r *RDB) ListLeaseExpired(cutoff time.Time, qnames ...string) ([]*base.Task
 			return nil, errors.E(op, errors.Internal, fmt.Sprintf("cast error: Lua script returned unexpected value: %v", res))
 		}
 		for _, s := range data {
-			if len(s) == 0 {
-				continue
-			}
 			msg, err := base.DecodeMessage([]byte(s))
 			if err != nil {
 				return nil, errors.E(op, errors.Internal, fmt.Sprintf("cannot decode message: %v", err))