TYPO3 Core

When executing commands on the command line (for example triggering the Scheduler) an exception is thrown.

Uncaught TYPO3 Exception Return value of "TYPO3\CMS\Scheduler\Command\SchedulerCommand::execute()" must be of the type int, NULL returned.
thrown in file [...]/vendor/symfony/console/Command/Command.php
in line 258

Symfony 5 expects an integer as the return value from Command::execute() in the Command class, see issue 33747 on GitHub (Symfony repository).

This change return 0 to satisfy Symfony version 5 requirements.