Hi Stefano.
Thanks for posting here. I can certainly help you here, but we can help you better if you create your own topic in the forum, where we can interact with you one on one. Also, we encourage you to post on your own topic because every time we post it will email the author of the topic.
Having said,
I was not able to reproduce the issue and the file works for me. Looking at line 23 it is just a bracket so I am not sure that would cause a fatal error.
What is the exact error you get and the file name it points to? Can you verify you are editing the correct file and what are using using to edit it?
So if you can let me know what you find out in a new topic we can help you there, but if you like you can still post what you find here.
Thanks