PHP message: PHP Fatal error:  Uncaught Error: Call to a member function id() on null in /opt/freshrss/freshrss/app/Controllers/importExportController.php:428
Stack trace:
#0 /opt/freshrss/freshrss/app/Controllers/importExportController.php(93): FreshRSS_importExport_Controller->importJson('{\n    "id": "us...', true)
#1 /opt/freshrss/freshrss/app/Controllers/importExportController.php(143): FreshRSS_importExport_Controller->importFile('freshrss_2018-0...', '/tmp/phpTQ99qz')
#2 /opt/freshrss/freshrss/lib/Minz/Dispatcher.php(118): FreshRSS_importExport_Controller->importAction()
#3 /opt/freshrss/freshrss/lib/Minz/Dispatcher.php(47): Minz_Dispatcher->launchAction('importAction')
#4 /opt/freshrss/freshrss/lib/Minz/FrontController.php(84): Minz_Dispatcher->run()
#5 /opt/freshrss/freshrss/p/i/index.php(46): Minz_FrontController->run()
#6 {main}

{
    "id": "user/bart/state/org.freshrss/starred",
    "title": "List of favourite articles",
    "author": "bart",
    "items": [

]}