[Config] fix filelocator with empty name

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

fix filelocator with empty name + phpdoc in config component
this is wrong. Other loaders than the FileLoader won't use the FileLoaderLoadException but any exception (the FileLoader is wrapping exceptions in a FileLoaderLoadException to add the info about which file is being loaded)