Unexpected end of JSON text when working with JSON_EXTRACT from derived table

This is a perfectly valid query, which should produce the ["a",1] JSON document:

select

  json_extract(t.j, '$')

from (

  select json_extract('["a",1]', '$') as j

) as t;

Yet it produces NULL and a warning:

> Unexpected end of JSON text in argument 1 to function 'json_extract'

A workaround appears to be to "format" the JSON value:

select

  json_extract(t.j, '$')

from (

  select json_extract('["a", 1]', '$') as j -- There's a whitespace in ["a", 1]

) as t;

Now, I'm getting the document as expected:

> ["a", 1]