As @Sgs noticed in T369551#10563466, migrateConfig.php (and setVersionData.php) throw a fatal if a provider is not supported:
InvalidArgumentException from line 102 of /srv/mediawiki/php-master/extensions/CommunityConfiguration/src/Provider/ConfigurationProviderFactory.php: Provider GrowthHomepage is not supported
#0 /srv/mediawiki/php-master/extensions/CommunityConfiguration/src/Provider/ConfigurationProviderFactory.php(115): MediaWiki\Extension\CommunityConfiguration\Provider\ConfigurationProviderFactory->getProviderSpec('GrowthHomepage')
#1 /srv/mediawiki/php-master/extensions/CommunityConfiguration/src/Provider/ConfigurationProviderFactory.php(165): MediaWiki\Extension\CommunityConfiguration\Provider\ConfigurationProviderFactory->constructProvider('GrowthHomepage')
#2 /srv/mediawiki/php-master/extensions/CommunityConfiguration/maintenance/migrateConfig.php(70): MediaWiki\Extension\CommunityConfiguration\Provider\ConfigurationProviderFactory->newProvider('GrowthHomepage')
#3 /srv/mediawiki/php-master/maintenance/includes/MaintenanceRunner.php(695): MediaWiki\Extension\CommunityConfiguration\Maintenance\MigrateConfig->execute()
#4 /srv/mediawiki/php-master/maintenance/run.php(51): MediaWiki\Maintenance\MaintenanceRunner->run()
#5 /srv/mediawiki/multiversion/MWScript.php(156): require_once('/srv/mediawiki/...')
#6 {main}This is not desirable, as it is not clear what is happening and why. Let's replace this with an error message that is understandable for humans.