CLI installer triggers debugging if langpack download fails (Fatal error in PHP 8.0)

Pre-requisites

1. Testing using PHP 8.0
2. Block network access to download.moodle.org, for instance, adding this in your local /etc/hosts file: 

   127.0.0.1    download.moodle.org

3. The test assumes a valid path of /var/www/moodledata to use as data root - modify as appropriate for your system
4. If you're using a Moodle folder with config.php, you'll need to remove it.

Testing

1. Execute the following command on a terminal:

   $ php admin/cli/install.php --lang=it --chmod=2777 --wwwroot=http://localhost:8000 --dataroot=/var/www/moodledata

2. Press return to confirm (it) default
3. Press return to confirm (2777) default
4. Press return to confirm (http://localhost:8000) default
5. Press return to confirm (/var/www/moodledata) default
6. Confirm no error/debugging notice was triggered, displaying the following:

   Undefined constant "NO_DEBUG_DISPLAY" in /var/www/html/lib/weblib.php:3270

7. Confirm you see the following text informing you that the lang pack could not be downloaded:

   <p>Lo scaricamento delle componenti non è andato a buon fine. Verificare le impostazioni del proxy. L'estensione PHP cURL è fortemente consigliata.</p>

   <p>Devi scaricare manualmente il file <a href="https://download.moodle.org/download.php/langpack/4.2/it.zip">https://download.moodle.org/download.php/langpack/4.2/it.zip</a>, copiarlo in "/var/www/moodledata/lang" e decomprimerlo.</p>

8. Press n to exit the installer
9. Re-enable network access to download.moodle.org
10. Run the CLI command again
11. Proceed to the step after confirming the location of data root:

    == Cartella dati ==

    inserisci un valore oppure premi Invio per usare il valore di default (/var/www/moodledata)

12. Confirm that the Italian language pack was successfully downloaded and extracted to /var/www/moodledata/lang/it
13. Complete installation