`JSON_ARRAY_APPEND` returns incorrect value for array arguments

[YangKeao]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

2. What did you expect to see? (Required)

mysql> SELECT JSON_ARRAY_APPEND('[1]', '$', JSON_ARRAY(2, 3));
+-------------------------------------------------+
| JSON_ARRAY_APPEND('[1]', '$', JSON_ARRAY(2, 3)) |
+-------------------------------------------------+
| [1, [2, 3]]                                     |
+-------------------------------------------------+
1 row in set (0.05 sec)

3. What did you see instead (Required)

mysql> SELECT JSON_ARRAY_APPEND('[1]', '$', JSON_ARRAY(2, 3));
+-------------------------------------------------+
| JSON_ARRAY_APPEND('[1]', '$', JSON_ARRAY(2, 3)) |
+-------------------------------------------------+
| [1, 2, 3]                                       |
+-------------------------------------------------+
1 row in set (0.01 sec)

4. What is your TiDB version? (Required)