query failed when some fields not exist against DOE

[BabySid]

Describe the bug
query failed when i run sql against doris on es. The prompt error is "inner hits node is not an array"

e.g.

CREATE EXTERNAL TABLE `case_replay_for_milimin` (
  `k1` varchar(20) NULL COMMENT "",
  `k2` varchar(20) NULL COMMENT "",
  `k3` varchar(20) NULL COMMENT "", 
) ENGINE=ELASTICSEARCH
COMMENT "ELASTICSEARCH"
PROPERTIES (
"hosts" = "...",
...
"enable_docvalue_scan" = "true"
)

This Table has rows like below :

> select  k1 from table;
+------+
| k1   |
+------+
| NULL |
| kkk1 |
| NULL |
+------+

but, actually it returns a error:

> select  k1 from table;
ERROR 1064 (HY000): inner hits node is not an array

To Reproduce
Steps to reproduce the behavior:

1. put values into index

PUT myindex/_doc/1
{
  "k1": "kkk1"
}
PUT myindex/_doc/2
{
  "k2": "kkk2"
}
PUT myindex/_doc/3
{
  "k3": "kkk3"
}

2、fetch fields contain k1,k2,k3. e.g. select k1,k2,k3 from table;

Expected behavior
ignore this situation and return ok

[wuyunfeng]

maybe you should emphasize have no value for one batch_size

[BabySid]

pr: #3513