occ guests:list execute return type exception

[joshtrichards]

 # sudo -u www-data php --define apc.enable_cli=1 /var/www/cloud.domain.tld/occ guests:list

No guests created
An unhandled exception has been thrown:
TypeError: Return value of "OCA\Guests\Command\ListCommand::execute()" must be of the type int, "null" returned. in /var/www/cloud.domain.tld3rdparty/symfony/console/Command/Command.php:301
Stack trace:
#0 /var/www/cloud.domain.tld/core/Command/Base.php(177): Symfony\Component\Console\Command\Command->run()
#1 /var/www/cloud.domain.tld/3rdparty/symfony/console/Application.php(1040): OC\Core\Command\Base->run()
#2 /var/www/cloud.domain.tld/3rdparty/symfony/console/Application.php(301): Symfony\Component\Console\Application->doRunCommand()
#3 /var/www/cloud.domain.tld/3rdparty/symfony/console/Application.php(171): Symfony\Component\Console\Application->doRun()
#4 /var/www/cloud.domain.tld/lib/private/Console/Application.php(206): Symfony\Component\Console\Application->run()
#5 /var/www/cloud.domain.tld/console.php(100): OC\Console\Application->run()
#6 /var/www/cloud.domain.tld/occ(11): require_once('...')

Originally posted by @JRGonz in nextcloud/server#42858 (comment)