Period is not working (Bug?)

Hi

Just quickly checked your code.

In inc/rest.php, you set the variable $date to be -1 month if period is equal to 3.

But then later on, you split (explode) the $date using the ‘-‘ as separator. Wouldn’t that lead to wrong start and end dates? I mean, the start date would then be "" (empty) and the end date would be " month". Using that today I get the following values for $args used later on in WP_Query():

Array
(
    [post_type] => attachment
    [post_status] => any
    [posts_per_page] => 1
    [offset] => 0
    [date_query] => Array
        (
            [after] => 01/01/1970
            [before] => 10/09/2017
        )

)

Is that a bug?