Drupal maintenance page - TypeError: Argument 1 passed to Drupal\Core\Extension\ThemeHandler::addTheme() must be an instance of Drupal\Core\Extension\Extension, null given

@cilefen is right with #12: watch that setting before patching stuff.

Nothing has been provided to indicate this is a core bug, sounds like a misconfiguration issue, so I am updating this to a support request. No activity lately so can probably close if no further updates in the next few months.

I am having this issue as well on core 10.3. After update of better exposed filters to version 7.0.0-beta1 composer removed the following modules withe the following error after drush updb
Currently using Missing or invalid modules The following modules are marked as installed in the core.extension
configuration, but they are missing:
* jquery_ui_datepicker
* jquery_ui_slider
* jquery_ui_touch_punch

Requirements check reports errors. Do you wish to continue? (yes/no) [yes]:
>

[success] No pending updates.
[warning] Undefined array key "bartik" theme.maintenance.inc:70
[error] TypeError: Drupal\Core\Extension\ThemeHandler::addTheme(): Argument #1 ($theme) must be of type Drupal\Core\Extension\Extension, null given, called in /var/www/html/web/core/includes/theme.maintenance.inc on line 70 in Drupal\Core\Extension\ThemeHandler->addTheme() (line 82 of /var/www/html/web/core/lib/Drupal/Core/Extension/ThemeHandler.php) #0 /var/www/html/web/core/includes/theme.maintenance.inc(70): Drupal\Core\Extension\ThemeHandler->addTheme(NULL)
#1 /var/www/html/web/core/includes/bootstrap.inc(324): _drupal_maintenance_theme()
#2 /var/www/html/web/core/includes/common.inc(492): drupal_maintenance_theme()
#3 /var/www/html/vendor/drush/drush/src/Commands/core/UpdateDBCommands.php(87): drupal_flush_all_caches()
#4 [internal function]: Drush\Commands\core\UpdateDBCommands->updatedb(Array)
#5 /var/www/html/vendor/consolidation/annotated-command/src/CommandProcessor.php(276): call_user_func_array(Array, Array)
#6 /var/www/html/vendor/consolidation/annotated-command/src/CommandProcessor.php(212): Consolidation\AnnotatedCommand\CommandProcessor->runCommandCallback(Array, Object(Consolidation\AnnotatedCommand\CommandData))
#7 /var/www/html/vendor/consolidation/annotated-command/src/CommandProcessor.php(176): Consolidation\AnnotatedCommand\CommandProcessor->validateRunAndAlter(Array, Array, Object(Consolidation\AnnotatedCommand\CommandData))
#8 /var/www/html/vendor/consolidation/annotated-command/src/AnnotatedCommand.php(391): Consolidation\AnnotatedCommand\CommandProcessor->process(Object(Symfony\Component\Console\Output\ConsoleOutput), Array, Array, Object(Consolidation\AnnotatedCommand\CommandData))
#9 /var/www/html/vendor/symfony/console/Command/Command.php(326): Consolidation\AnnotatedCommand\AnnotatedCommand->execute(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#10 /var/www/html/vendor/symfony/console/Application.php(1096): Symfony\Component\Console\Command\Command->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#11 /var/www/html/vendor/symfony/console/Application.php(324): Symfony\Component\Console\Application->doRunCommand(Object(Consolidation\AnnotatedCommand\AnnotatedCommand), Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#12 /var/www/html/vendor/symfony/console/Application.php(175): Symfony\Component\Console\Application->doRun(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#13 /var/www/html/vendor/drush/drush/src/Runtime/Runtime.php(110): Symfony\Component\Console\Application->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#14 /var/www/html/vendor/drush/drush/src/Runtime/Runtime.php(40): Drush\Runtime\Runtime->doRun(Array, Object(Symfony\Component\Console\Output\ConsoleOutput))
#15 /var/www/html/vendor/drush/drush/drush.php(139): Drush\Runtime\Runtime->run(Array)
#16 /var/www/html/vendor/drush/drush/drush(4): require('/var/www/html/v...')
#17 /var/www/html/vendor/bin/drush(119): include('/var/www/html/v...')
#18 {main}.

message is repeated again followed by

TypeError: Drupal\Core\Extension\ThemeHandler::addTheme(): Argument #1 ($theme) must be of type Drupal\Core\Extension\Extension, null given, called in /var/www/html/web/core/includes/theme.maintenance.inc on line 70 in Drupal\Core\Extension\ThemeHandler->addTheme() (line 82 of /var/www/html/web/core/lib/Drupal/Core/Extension/ThemeHandler.php).
[warning] Drush command terminated abnormally.
Failed to run drush updb: exit status 1

Attempting to delete the missing modules

drush config-delete core.extension.jquery_ui_datepicker
[error] Config core.extension.jquery_ui_datepicker does not exist
Failed to run drush config-delete core.extension.jquery_ui_datepicker: exit status 1