Steps to reproduce the issue

Try to install an extension from invalid URL, debug is enabled.

Expected result

See only "Could not open..." Joomla warning.

Actual result

PHP error

An error has occurred.
0 Joomla\CMS\Event\Installer\InstallerEvent::onSetPackage(): Argument #1 ($value) must be of type ?array, bool given, called in \libraries\src\Event\AbstractEvent.php on line 225

System information (as much as possible)

Joomla5 nightly

Additional comments