Fatal error in ActivityMonitor with version 5.10.*

[kasperg]

When using the newly release version 5.10.* we run into a fatal error in our deployment scripts which run the Upsun CLI:

    W: Fatal error: Uncaught TypeError: Platformsh\Cli\Service\ActivityMonitor::formatResult(): Return value must be of type string, null returned in phar:///tmp/upsun-tmp/legacy-5.10.2/upsun.phar/src/Service/ActivityMonitor.php:604
    W: Stack trace:
    W: #0 phar:///tmp/upsun-tmp/legacy-5.10.2/upsun.phar/src/Command/Activity/ActivityListCommand.php(139): Platformsh\Cli\Service\ActivityMonitor::formatResult(Object(Platformsh\Client\Model\Activity), false)
    W: #1 phar:///tmp/upsun-tmp/legacy-5.10.2/upsun.phar/vendor/symfony/console/Command/Command.php(341): Platformsh\Cli\Command\Activity\ActivityListCommand->execute(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
    W: #2 phar:///tmp/upsun-tmp/legacy-5.10.2/upsun.phar/vendor/symfony/console/Application.php(1102): Symfony\Component\Console\Command\Command->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
    W: #3 phar:///tmp/upsun-tmp/legacy-5.10.2/upsun.phar/src/Application.php(397): Symfony\Component\Console\Application->doRunCommand(Object(Platformsh\Cli\Command\Activity\ActivityListCommand), Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
    W: #4 phar:///tmp/upsun-tmp/legacy-5.10.2/upsun.phar/vendor/symfony/console/Application.php(356): Platformsh\Cli\Application->doRunCommand(Object(Platformsh\Cli\Command\Activity\ActivityListCommand), Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
    W: #5 phar:///tmp/upsun-tmp/legacy-5.10.2/upsun.phar/vendor/symfony/console/Application.php(195): Symfony\Component\Console\Application->doRun(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
    W: #6 phar:///tmp/upsun-tmp/legacy-5.10.2/upsun.phar/bin/platform(32): Symfony\Component\Console\Application->run()
    W: #7 /tmp/upsun-tmp/legacy-5.10.2/upsun.phar(4): require('phar:///tmp/ups...')

The situation can be seen in project p25h2mlngovee

Activities:

• Success / Platform.sh CLI v. 5.9.0: j76kjq5tw2zue
• Error / Upsun CLI v. 5.10.0: roe4b4ra6jime
• Error / Upsun CLI v. 5.10.2: in2citefirlgk