[Bug] An analysis error will report when there are different types in case-when-then-else with group by clause

[xy720]

Describe the bug
If there are different scalar types in case-when-then-else with group by clause, an error will report.

For example, there is a 9 columns table named test_tbl:

+----------------------+-------------+------+-------+---------------------+---------+
| Field                | Type        | Null | Key   | Default             | Extra   |
+----------------------+-------------+------+-------+---------------------+---------+
| event_day            | INT         | No   | true  | NULL                |         |
| event_hour           | TINYINT     | No   | true  | 0                   |         |
| event_minute         | TINYINT     | No   | true  | 0                   |         |
| event_time           | DATETIME    | No   | true  | 1970-01-01 00:00:00 |         |
| search_page          | VARCHAR(30) | No   | true  |                     |         |
| search_source        | TINYINT     | No   | true  | 0                   |         |
| soft_version         | VARCHAR(30) | No   | true  |                     |         |
| not_arrived_category | VARCHAR(30) | No   | true  |                     |         |
| pv                   | FLOAT       | No   | false | 0                   | REPLACE |
+----------------------+-------------+------+-------+---------------------+---------+

CREATE TABLE `baiduapp_strategy_performance_search_ios_arrive` (
  `event_day` int(11) NOT NULL COMMENT "日期,如20191016",
  `event_hour` tinyint(4) NOT NULL DEFAULT "0" COMMENT "小时,如8",
  `event_minute` tinyint(4) NOT NULL DEFAULT "0" COMMENT "分钟,如59",
  `event_time` datetime NOT NULL DEFAULT "1970-01-01 00:00:00" COMMENT "隶属时间(区间查询用)",
  `search_page` varchar(30) NOT NULL DEFAULT "" COMMENT "page来源",
  `search_source` tinyint(4) NOT NULL DEFAULT "0" COMMENT "search_source来源",
  `soft_version` varchar(30) NOT NULL DEFAULT "" COMMENT "APP版本,如11.15.0.2",
  `not_arrived_category` varchar(30) NOT NULL DEFAULT "" COMMENT "未到达原因",
  `pv` float NOT NULL DEFAULT "0" COMMENT "聚合pv数"
) ENGINE=OLAP
UNIQUE KEY(`event_day`, `event_hour`, `event_minute`, `event_time`, `search_page`, `search_source`, `soft_version`, `not_arrived_category`)
COMMENT "OLAP"
PARTITION BY RANGE(`event_day`)
(PARTITION p202006 VALUES [("20200601"), ("20200701")),
PARTITION p202007 VALUES [("20200701"), ("20200801")),
PARTITION p202008 VALUES [("20200801"), ("20200901")),
PARTITION p202009 VALUES [("20200901"), ("20201001")),
PARTITION p202010 VALUES [("20201001"), ("20201101")),
PARTITION p202011 VALUES [("20201101"), ("20201201")),
PARTITION p202012 VALUES [("20201201"), ("20210101")))
DISTRIBUTED BY HASH(`event_day`) BUCKETS 16
PROPERTIES (
"replication_num" = "3",
"in_memory" = "false",
"storage_format" = "V2"
);

The following sql will report an analysis error.

SELECT
    a.event_day,
    a.search_page,
    GROUP_CONCAT(a.search_source) AS search_source,
    a.soft_version,
    sum(b.pv) AS daoda_pv,
    sum(b.new_pv) AS new_daoda_pv,
    sum(a.pv) AS total_pv,
    sum(b.pv) / sum(a.pv) * 100 AS arrived_rate,
    sum(b.new_pv) / sum(a.pv) * 100 AS new_arrived_rate
FROM
(
    SELECT
        event_day,
        case when '' = '' then 'all' else '' end as search_page,
        case when "('1','2','5')" = '' then 'all' else search_source end as search_source,
        case when '' = '' then 'all' else '' end as soft_version,
        SUM(pv) AS pv
    FROM baiduapp_strategy_performance_search_ios_arrive
    WHERE event_day BETWEEN 20200908 and 20200914
    AND 1=1
    AND search_source in ('1','2','5')
    AND 1=1
    AND soft_version >= '11.23.0.0'
    GROUP BY event_day,search_page,search_source,soft_version
    ORDER BY search_source
) a 
LEFT JOIN
(
    SELECT
        event_day,
        case when '' = '' then 'all' else '' end as search_page,
        case when "('1','2','5')" = '' then 'all' else search_source end as search_source,
        case when '' = '' then 'all' else '' end as soft_version,
        SUM(if(not_arrived_category = '', pv, 0)) AS pv,
        SUM(pv) AS new_pv
    FROM baiduapp_strategy_performance_search_ios_arrive
    WHERE event_day BETWEEN 20200908 and 20200914
    AND 1=1
    AND search_source in ('1','2','5')
    AND 1=1
    AND not_arrived_category in ('', 'stay_too_short')
    AND soft_version >= '11.23.0.0'
    GROUP BY event_day,search_page,search_source,soft_version
    ORDER BY search_source
) b ON a.event_day = b.event_day
   AND a.search_page = b.search_page
   AND a.search_source = b.search_source
   AND a.soft_version = b.soft_version
GROUP BY
    a.event_day,
    a.search_page,
    a.soft_version
ORDER BY event_day DESC
limit 0, 5000