Error when adding ics feed

I get the following error in my dashboard when adding or editing a new ics calendar feed (webcal://stanza.co/api/schedules/ua/m-basebl.ics):

All-in-One Event Calendar has been disabled due to an error:
Argument 1 passed to Ai1ec_Ics_Import_Export_Engine::_is_timeless() must be an array, null given, called in /srv/www/wvuafm/wp-content/plugins/all-in-one-event-calendar/lib/import-export/ics.php on line 263 and defined
Error Details:
#0 /srv/www/wvuafm/wp-content/plugins/all-in-one-event-calendar/lib/import-export/ics.php(106): Ai1ec_Exception_Handler->handle_error(4096, ‘Argument 1 pass…’, ‘/srv/www/wvuafm…’, 106, Array)
#1 /srv/www/wvuafm/wp-content/plugins/all-in-one-event-calendar/lib/import-export/ics.php(263): Ai1ec_Ics_Import_Export_Engine->_is_timeless(NULL)
#2 /srv/www/wvuafm/wp-content/plugins/all-in-one-event-calendar/lib/import-export/ics.php(38): Ai1ec_Ics_Import_Export_Engine->add_vcalendar_events_to_db(Object(vcalendar), Array)
#3 /srv/www/wvuafm/wp-content/plugins/all-in-one-event-calendar/app/controller/import-export.php(87): Ai1ec_Ics_Import_Export_Engine->import(Array)
#4 /srv/www/wvuafm/wp-content/plugins/all-in-one-event-calendar/lib/calendar-feed/ics.php(154): Ai1ec_Import_Export_Controller->import_events(‘ics’, Array)
#5 /srv/www/wvuafm/wp-content/plugins/all-in-one-event-calendar/lib/calendar-feed/ics.php(76): Ai1ecIcsConnectorPlugin->process_ics_feed_update(false, ‘2’)
#6 /srv/www/wvuafm/wp-content/plugins/all-in-one-event-calendar/lib/calendar-feed/ics.php(575): Ai1ecIcsConnectorPlugin->update_ics_feed(‘2’)
#7 /srv/www/wvuafm/wp-content/plugins/all-in-one-event-calendar/lib/bootstrap/registry/object.php(209): Ai1ecIcsConnectorPlugin->add_ics_feed(”)
#8 /srv/www/wvuafm/wp-content/plugins/all-in-one-event-calendar/lib/event/callback/abstract.php(59): Ai1ec_Registry_Object->dispatch(‘calendar-feed.i…’, ‘add_ics_feed’, Array)
#9 [internal function]: Ai1ec_Event_Callback_Abstract->run(”)
#10 /srv/www/wvuafm/wp-includes/plugin.php(525): call_user_func_array(Array, Array)
#11 /srv/www/wvuafm/wp-admin/admin-ajax.php(89): do_action(‘wp_ajax_ai1ec_a…’)
#12 {main}
Request Uri: /wp-admin/admin-ajax.php

The error turns off the All-in-One Event Calendar plugin. Any idea what might be causing the error?

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