Get E_ERROR when creating a schedule

Fehler-Details ============== Ein Fehler vom Typ E_ERROR wurde in der Zeile 20 der Datei /xy/xyz/www/myhomepage.com/wp-content/plugins/wp-crontrol/src/schedule.php verursacht. Fehlermeldung: Uncaught TypeError: Cannot access offset of type string on string in /xy/xyz/www/myhomepage.com/wp-content/plugins/wp-crontrol/src/schedule.php:20 Stack trace: #0 ~/wp-content/plugins/wp-crontrol/src/bootstrap.php(430): Crontrol\Schedule\add(‘every_10_minute…’, 300, ‘Every 10 Minute…’) #1 ~/wp-includes/class-wp-hook.php(324): Crontrol\action_handle_posts(”) #2 ~/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters(NULL, Array) #3 ~/wp-includes/plugin.php(517): WP_Hook->do_action(Array) #4 ~/wp-settings.php(643): do_action(‘init’) #5 ~/wp-config.php(108): require_once(‘/xy/xyz/…’) #6 ~/wp-load.php(50): require_once(‘/xy/xyz/…’) #7 ~/wp-admin/admin.php(34): require_once(‘/xy/xyz/…’) #8 ~/wp-admin/options-general.php(10): require_once(‘/xy/xyz/…’) #9 {main} thrown