If the file config.php does not exist in site/config directory then create one and set debug to true
<?php
return [
'debug' => true,
];
This will log out any error with a useful message in your browser when something is not right.
You probably don't want to log this error in production. Therefore you can create a second config file for working locally. So let's set the already created config.php file debug property to false. And create another config file for development only. Next to config.php create config.localhost.php and set the debug propery to true. This way debug mode will only be set to true when domain is localhost.