Try running: php maintenance/update.php --quick --force with Flow and CentralAuth extensions installed.
[e02fe80e57668032e5ebfc00] [no req] TypeError from line 184 of /usr/local/var/www/wiki/mw-core/extensions/CentralAuth/includes/CentralAuthUser.php: Argument 1 passed to CentralAuthUser::getMasterInstance() must be an instance of User, null given, called in /usr/local/var/www/wiki/mw-core/extensions/Flow/includes/TalkpageManager.php on line 254
Backtrace:
#0 /usr/local/var/www/wiki/mw-core/extensions/Flow/includes/TalkpageManager.php(254): CentralAuthUser::getMasterInstance(NULL)
#1 /usr/local/var/www/wiki/mw-core/extensions/Flow/maintenance/FlowCreateTemplates.php(114): Flow\TalkpageManager->getTalkpageManager()
#2 /usr/local/var/www/wiki/mw-core/extensions/Flow/maintenance/FlowCreateTemplates.php(86): FlowCreateTemplates->create(Title, WikitextContent)
#3 /usr/local/var/www/wiki/mw-core/maintenance/Maintenance.php(1730): FlowCreateTemplates->doDBUpdates()
#4 /usr/local/var/www/wiki/mw-core/maintenance/update.php(221): LoggedUpdateMaintenance->execute()
#5 /usr/local/var/www/wiki/mw-core/maintenance/doMaintenance.php(99): UpdateMediaWiki->execute()
#6 /usr/local/var/www/wiki/mw-core/maintenance/update.php(281): require_once(string)
#7 {main}Notes
MediaWiki 1.34-alpha
PHP: 7.3.8
The issue is this piece of code;
$user = User::newSystemUser( FLOW_TALK_PAGE_MANAGER_USER, [ 'steal' => true ] );
because User::newSystemUser() can return null but CentralAuthUser::getMasterInstance() expects strictly only a User object.