NULL is a valid JSON document

Using the following test table:

CREATE TABLE `test` (

	`extra_info` BLOB NULL DEFAULT NULL

)

COLLATE='utf8_general_ci'

ENGINE=InnoDB

;

INSERT INTO `test` VALUES (NULL, 1);

And then running the following queries:

SELECT json_valid(null);      # returns null, should return 1?

SELECT json_valid('{}');        # returns 1

UPDATE test

SET extra_info = JSON_SET(extra_info, '$.service_supplier_id', 999)

WHERE test_int = 1;

I expect a new JSON document to be created as per JSON lint and RFC 7159 as per the following URL's as NULL is a valid JSON document.

https://stackoverflow.com/questions/8526995/is-null-valid-json-4-bytes-nothing-else
https://jsonlint.com/

This goes against the MariaDB documentation that states NULL will result in a NULL document:

Updates or inserts data into a JSON document, returning the result, or NULL if any of the arguments are NULL or the optional path fails to find an object.

I think MariaDB implements an older JSON standard preventing creation of a new document into a NULL column. Or is there another way to achieve the above JSON_SET to create a new document?