Describe the bug
Trying to programmatically delete subpage drafts within a page.changeStatus:after hook, throws the following error: SyntaxError: Unexpected token T in JSON at position 0

3/5 pages get deleted, 2/5 (identical) don’t.

Here is the config.php

'page.changeStatus:after' => function ($newPage, $oldPage) {
            if($newPage->intendedTemplate() == 'project' && $newPage->status() == 'unlisted') {
                foreach($newPage->drafts() as $phase) {
                    try {
                        $phase->delete();
                        echo 'The page has been deleted';
                    } catch(Exception $e) {
                        echo $e->getMessage();
                    }
                }   
            }
        }

To Reproduce
Steps to reproduce the behavior:

1. Add subpages to parent page
2. Change status from listed to unlisted for parent page through the panel
3. See error

Expected behavior
All pages should be deleted.

Kirby Version
3.0.0-beta-6.22

Desktop (please complete the following information):

• OS: OSX
• Browser Chrome
• Version 70