Hi,

Maybe a little bit special, but i got an error because of undefined Service for `monolog.logger.pimcore` while Check Requirements Route.

The Exception:
```
request.CRITICAL: Uncaught PHP Exception Symfony\Component\DependencyInjection\Exception\ServiceNotFoundException: "You have requested a non-existent service "monolog.logger.pimcore". Did you mean one of these: "monolog.logger.event", "monolog.logger.php", "monolog.logger.request", "monolog.logger.cache", "monolog.logger.console"?" at /var/www/html/client.local/vendor/symfony/symfony/src/Symfony/Component/DependencyInjection/Container.php line 348 {"exception":"[object] (Symfony\\Component\\DependencyInjection\\Exception\\ServiceNotFoundException(code: 0): You have requested a non-existent service \"monolog.logger.pimcore\". Did you mean one of these: \"monolog.logger.event\", \"monolog.logger.php\", \"monolog.logger.request\", \"monolog.logger.cache\", \"monolog.logger.console\"? at /var/www/html/client.local/vendor/symfony/symfony/src/Symfony/Component/DependencyInjection/Container.php:348)"} []
```

It is caused because of Pimcore\Logger usage of some Methods like `Pimcore\Config::getSystemConfig()`

An Example ExceptionTrace (Working dir is replaced with `./`)
````
#0 ./pimcore/lib/Pimcore/Logger.php(29): Symfony\Component\DependencyInjection\Container->get('monolog.logger....')
#1 ./pimcore/lib/Pimcore/Logger.php(44): Pimcore\Logger::log('Cannot find sys...', 'emergency', Array)
pimcore#2 ./pimcore/lib/Pimcore/Config.php(114): Pimcore\Logger::emergency('Cannot find sys...')
pimcore#3 ./pimcore/lib/Pimcore/Tool/Console.php(80): Pimcore\Config::getSystemConfig()
pimcore#4 ./pimcore/lib/Pimcore/Tool/Console.php(233): Pimcore\Tool\Console::getExecutable('php', true)
pimcore#5 ./pimcore/lib/Pimcore/Tool/Requirements.php(328): Pimcore\Tool\Console::getPhpCli()
pimcore#6 ./pimcore/lib/Pimcore/Bundle/InstallBundle/Controller/InstallController.php(88): Pimcore\Tool\Requirements::checkExternalApplications()
pimcore#7 ./vendor/symfony/symfony/src/Symfony/Component/HttpKernel/HttpKernel.php(151): Pimcore\Bundle\InstallBundle\Controller\InstallController->checkAction(Object(Symfony\Component\HttpFoundation\Request), Object(Pimcore\Install\Installer))
pimcore#8 ./vendor/symfony/symfony/src/Symfony/Component/HttpKernel/HttpKernel.php(68): Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object(Symfony\Component\HttpFoundation\Request), 1)
pimcore#9 ./vendor/symfony/symfony/src/Symfony/Component/HttpKernel/Kernel.php(202): Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
pimcore#10./web/install.php(72): Symfony\Component\HttpKernel\Kernel->handle(Object(Symfony\Component\HttpFoundation\Request))
pimcore#11 {main}
````

best regards

Error displaying at the time of class creation using admin, on line 312. I just make change  if ($data != null && method_exists($data, 'getChildren')) { 


Error was as below : 

Timestamp: Sun Mar 07 2021 09:28:58 GMT+0530 (India Standard Time)
Status: 500 | Internal Server Error
URL: /admin/class/add
Method: POST
Message: method_exists(): Argument #1 ($object_or_class) must be of type object|string, null given
Trace: 
in /var/www/html/vendor/pimcore/pimcore/models/DataObject/ClassDefinition.php:311
#0 /var/www/html/vendor/pimcore/pimcore/models/DataObject/ClassDefinition.php(311): method_exists(NULL, 'getChildren')
#1 /var/www/html/vendor/pimcore/pimcore/models/DataObject/ClassDefinition.php(584): Pimcore\Model\DataObject\ClassDefinition::cleanupForExport(NULL)
pimcore#2 /var/www/html/vendor/pimcore/pimcore/models/DataObject/ClassDefinition.php(372): Pimcore\Model\DataObject\ClassDefinition->generateClassFiles(true)
pimcore#3 /var/www/html/vendor/pimcore/pimcore/bundles/AdminBundle/Controller/Admin/DataObject/ClassController.php(261): Pimcore\Model\DataObject\ClassDefinition->save(true)
pimcore#4 /var/www/html/vendor/symfony/symfony/src/Symfony/Component/HttpKernel/HttpKernel.php(157): Pimcore\Bundle\AdminBundle\Controller\Admin\DataObject\ClassController->addAction(Object(Symfony\Component\HttpFoundation\Request))
pimcore#5 /var/www/html/vendor/symfony/symfony/src/Symfony/Component/HttpKernel/HttpKernel.php(79): Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object(Symfony\Component\HttpFoundation\Request), 1)
pimcore#6 /var/www/html/vendor/symfony/symfony/src/Symfony/Component/HttpKernel/Kernel.php(195): Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
pimcore#7 /var/www/html/public/index.php(35): Symfony\Component\HttpKernel\Kernel->handle(Object(Symfony\Component\HttpFoundation\Request))
pimcore#8 {main}

Can not filter checkbox values in Grid.

Fatal Error
File - vendor/doctrine/dbal/src/Connection.php
Line - 568
Trace - Doctrine\DBAL\Connection::quote(): Argument pimcore#1 ($value) must be of type string, int given, called in vendor/pimcore/pimcore/models/DataObject/ClassDefinition/Data/Checkbox.php on line 174
Trace - #0 vendor/pimcore/pimcore/models/DataObject/ClassDefinition/Data/Checkbox.php(174): Doctrine\DBAL\Connection->quote()
pimcore#1 vendor/pimcore/pimcore/models/DataObject/ClassDefinition/Data/Checkbox.php(158): Pimcore\Model\DataObject\ClassDefinition\Data\Checkbox->getFilterConditionExt()
pimcore#2 vendor/pimcore/admin-ui-classic-bundle/src/Helper/GridHelperService.php(366): Pimcore\Model\DataObject\ClassDefinition\Data\Checkbox->getFilterCondition()
pimcore#3 vendor/pimcore/admin-ui-classic-bundle/src/Helper/GridHelperService.php(667): Pimcore\Bundle\AdminBundle\Helper\GridHelperService->getFilterCondition()
pimcore#4 vendor/pimcore/admin-ui-classic-bundle/src/Controller/Admin/DataObject/DataObjectActionsTrait.php(102): Pimcore\Bundle\AdminBundle\Helper\GridHelperService->prepareListingForGrid()
pimcore#5 vendor/pimcore/admin-ui-classic-bundle/src/Controller/Admin/DataObject/DataObjectController.php(1693): Pimcore\Bundle\AdminBundle\Controller\Admin\DataObject\DataObjectController->gridProxy()
pimcore#6 vendor/symfony/http-kernel/HttpKernel.php(181): Pimcore\Bundle\AdminBundle\Controller\Admin\DataObject\DataObjectController->gridProxyAction()
pimcore#7 vendor/symfony/http-kernel/HttpKernel.php(76): Symfony\Component\HttpKernel\HttpKernel->handleRaw()
pimcore#8 vendor/symfony/http-kernel/Kernel.php(197): Symfony\Component\HttpKernel\HttpKernel->handle()
pimcore#9 vendor/symfony/runtime/Runner/Symfony/HttpKernelRunner.php(35): Symfony\Component\HttpKernel\Kernel->handle()
pimcore#10 vendor/autoload_runtime.php(29): Symfony\Component\Runtime\Runner\Symfony\HttpKernelRunner->run()
pimcore#11 public/index.php(19): require_once('...')
pimcore#12 {main}

Can not filter checkbox values in Grid.

Fatal Error
File - vendor/doctrine/dbal/src/Connection.php
Line - 568
Trace - Doctrine\DBAL\Connection::quote(): Argument pimcore#1 ($value) must be of type string, int given, called in vendor/pimcore/pimcore/models/DataObject/ClassDefinition/Data/Checkbox.php on line 174
Trace - #0 vendor/pimcore/pimcore/models/DataObject/ClassDefinition/Data/Checkbox.php(174): Doctrine\DBAL\Connection->quote()
pimcore#1 vendor/pimcore/pimcore/models/DataObject/ClassDefinition/Data/Checkbox.php(158): Pimcore\Model\DataObject\ClassDefinition\Data\Checkbox->getFilterConditionExt()
pimcore#2 vendor/pimcore/admin-ui-classic-bundle/src/Helper/GridHelperService.php(366): Pimcore\Model\DataObject\ClassDefinition\Data\Checkbox->getFilterCondition()
pimcore#3 vendor/pimcore/admin-ui-classic-bundle/src/Helper/GridHelperService.php(667): Pimcore\Bundle\AdminBundle\Helper\GridHelperService->getFilterCondition()
pimcore#4 vendor/pimcore/admin-ui-classic-bundle/src/Controller/Admin/DataObject/DataObjectActionsTrait.php(102): Pimcore\Bundle\AdminBundle\Helper\GridHelperService->prepareListingForGrid()
pimcore#5 vendor/pimcore/admin-ui-classic-bundle/src/Controller/Admin/DataObject/DataObjectController.php(1693): Pimcore\Bundle\AdminBundle\Controller\Admin\DataObject\DataObjectController->gridProxy()
pimcore#6 vendor/symfony/http-kernel/HttpKernel.php(181): Pimcore\Bundle\AdminBundle\Controller\Admin\DataObject\DataObjectController->gridProxyAction()
pimcore#7 vendor/symfony/http-kernel/HttpKernel.php(76): Symfony\Component\HttpKernel\HttpKernel->handleRaw()
pimcore#8 vendor/symfony/http-kernel/Kernel.php(197): Symfony\Component\HttpKernel\HttpKernel->handle()
pimcore#9 vendor/symfony/runtime/Runner/Symfony/HttpKernelRunner.php(35): Symfony\Component\HttpKernel\Kernel->handle()
pimcore#10 vendor/autoload_runtime.php(29): Symfony\Component\Runtime\Runner\Symfony\HttpKernelRunner->run()
pimcore#11 public/index.php(19): require_once('...')
pimcore#12 {main}

Can not filter checkbox values in Grid.

Fatal Error
File - vendor/doctrine/dbal/src/Connection.php
Line - 568
Trace - Doctrine\DBAL\Connection::quote(): Argument #1 ($value) must be of type string, int given, called in vendor/pimcore/pimcore/models/DataObject/ClassDefinition/Data/Checkbox.php on line 174
Trace - #0 vendor/pimcore/pimcore/models/DataObject/ClassDefinition/Data/Checkbox.php(174): Doctrine\DBAL\Connection->quote()
#1 vendor/pimcore/pimcore/models/DataObject/ClassDefinition/Data/Checkbox.php(158): Pimcore\Model\DataObject\ClassDefinition\Data\Checkbox->getFilterConditionExt()
#2 vendor/pimcore/admin-ui-classic-bundle/src/Helper/GridHelperService.php(366): Pimcore\Model\DataObject\ClassDefinition\Data\Checkbox->getFilterCondition()
#3 vendor/pimcore/admin-ui-classic-bundle/src/Helper/GridHelperService.php(667): Pimcore\Bundle\AdminBundle\Helper\GridHelperService->getFilterCondition()
#4 vendor/pimcore/admin-ui-classic-bundle/src/Controller/Admin/DataObject/DataObjectActionsTrait.php(102): Pimcore\Bundle\AdminBundle\Helper\GridHelperService->prepareListingForGrid()
#5 vendor/pimcore/admin-ui-classic-bundle/src/Controller/Admin/DataObject/DataObjectController.php(1693): Pimcore\Bundle\AdminBundle\Controller\Admin\DataObject\DataObjectController->gridProxy()
#6 vendor/symfony/http-kernel/HttpKernel.php(181): Pimcore\Bundle\AdminBundle\Controller\Admin\DataObject\DataObjectController->gridProxyAction()
#7 vendor/symfony/http-kernel/HttpKernel.php(76): Symfony\Component\HttpKernel\HttpKernel->handleRaw()
#8 vendor/symfony/http-kernel/Kernel.php(197): Symfony\Component\HttpKernel\HttpKernel->handle()
#9 vendor/symfony/runtime/Runner/Symfony/HttpKernelRunner.php(35): Symfony\Component\HttpKernel\Kernel->handle()
#10 vendor/autoload_runtime.php(29): Symfony\Component\Runtime\Runner\Symfony\HttpKernelRunner->run()
#11 public/index.php(19): require_once('...')
#12 {main}