Problem description: If the webserver doesn't have rights to update the zabbix.conf.php file, the following runtime error is observed along with the error message in frontend, when completing zabbix frontend setup form (setup.php):

file_put_contents(/home/jenkins/workspace/zabbix-dev/frontend/sources/ui/conf/zabbix.conf.php): failed to open stream: Permission denied [setup.php:130 -> CTag->__construct() -> CTag->addItem() -> CObject->addItem() -> CTag->addItem() -> CObject->addItem() -> unpack_object() -> CTag->toString() -> CSetupWizard->bodyToString() -> CSetupWizard->getStage() -> CSetupWizard->stage5() -> CConfigFile->save() -> file_put_contents() -> CConfigFile->{closure}() in include/classes/core/CConfigFile.php:190]

No runtime errors should be thrown, only the frontend error message should be shown.

Steps to reproduce:

1. Make sure Your webserver doesn't have permissions to update the zabbix.conf.php file.
2. Open zabbix frontend configuration form (setup.php)
3. Go through all sections of this form untill You reach "Install" section
4. In the "Install" section press "Finish" button - make sure that the "Cannot create the configuration file" error message is displayed
5. Check for runtime errors.

Result: the previously mentioned runtime error is observed.

Expected: no runtime errors should be thrown, only the frontend error message should be shown.