PHP Fatal error: Uncaught TypeError thrown if invalid alias used

[cgmonroe]

Describe the bug
If you enter an invalid/ undefined alias on a drush command, you do not get a "Unknown alias" or similar error. Instead you get a PHP Fatal error: with no other explanation.

To Reproduce
The command:

drush @xxx.xxx status

Returns the PhP Fatal errors.

Also happens if the group is valid but site name is wrong, e.g. drush @my-sites.wrong-alias status

Expected behavior
The expected behavior would be just a message like:

[preflight] The alias @xxx.xxx could not be found.

Actual behavior
The command returns this error stack trace.

PHP Fatal error: Uncaught TypeError: Return value of Drush\Preflight\PreflightSiteLocator::determineSelf() must be an instance of Consolidation\SiteAlias\SiteAlias, bool returned in /app/vendor/drush/drush/src/Preflight/PreflightSiteLocator.php:68
Stack trace:
#0 /app/vendor/drush/drush/src/Preflight/PreflightSiteLocator.php(39): Drush\Preflight\PreflightSiteLocator->determineSelf(Object(Drush\Preflight\PreflightArgs), Object(Drush\Config\Environment), '/app/docroot')
#1 /app/vendor/drush/drush/src/Preflight/Preflight.php(286): Drush\Preflight\PreflightSiteLocator->findSite(Object(Drush\Preflight\PreflightArgs), Object(Drush\Config\Environment), '/app/docroot')
#2 /app/vendor/drush/drush/src/Runtime/Runtime.php(69): Drush\Preflight\Preflight->preflight(Array)
#3 /app/vendor/drush/drush/src/Runtime/Runtime.php(51): Drush\Runtime\Runtime->doRun(Array, Object(Symfony\Component\Console\Output\ConsoleOutput))
#4 /app/vendor/drush/drush/drush.php(72): Drush\Runtime\Runtime->run(Array)
#5 /app/vendor/drush/drush/drush(3): require('/ in /app/vendor/drush/drush/src/Preflight/PreflightSiteLocator.php on line 68

Fatal error: Uncaught TypeError: Return value of Drush\Preflight\PreflightSiteLocator::determineSelf() must be an instance of Consolidation\SiteAlias\SiteAlias, bool returned in /app/vendor/drush/drush/src/Preflight/PreflightSiteLocator.php:68
Stack trace:
#0 /app/vendor/drush/drush/src/Preflight/PreflightSiteLocator.php(39): Drush\Preflight\PreflightSiteLocator->determineSelf(Object(Drush\Preflight\PreflightArgs), Object(Drush\Config\Environment), '/app/docroot')
#1 /app/vendor/drush/drush/src/Preflight/Preflight.php(286): Drush\Preflight\PreflightSiteLocator->findSite(Object(Drush\Preflight\PreflightArgs), Object(Drush\Config\Environment), '/app/docroot')
#2 /app/vendor/drush/drush/src/Runtime/Runtime.php(69): Drush\Preflight\Preflight->preflight(Array)
#3 /app/vendor/drush/drush/src/Runtime/Runtime.php(51): Drush\Runtime\Runtime->doRun(Array, Object(Symfony\Component\Console\Output\ConsoleOutput))
#4 /app/vendor/drush/drush/drush.php(72): Drush\Runtime\Runtime->run(Array)
#5 /app/vendor/drush/drush/drush(3): require('/ in /app/vendor/drush/drush/src/Preflight/PreflightSiteLocator.php on line 68

Workaround
Drop back to Drush 10.

System Configuration

Q	A
Drush version?	11.1.1
Drupal version?	9.4.5
PHP version	7.4
OS?	Mac using Lando drupal9 setup. / Also tested in Acquia server shell - same result

Additional information
None.

[weitzman]

Fixed in #5239