Custom library path + custom library, without slash in its name, results in exception

[distahl]

Describe the bug

I've added a custom library path for icingaweb2 in the apache config. After that I created my own library in this path. The name of the library (composer.json) does not contain any slash. When I now navigate to configuration->module and view other modules having dependencies, like vspheredb or icingadb, I get this exception:

Undefined offset: 1
#0 /usr/share/php/Icinga/Application/Libraries.php(82): Icinga\Application\ApplicationBootstrap->Icinga\Application\{closure}()
#1 /usr/share/php/Icinga/Application/Libraries.php(52): Icinga\Application\Libraries->get()
#2 /usr/share/php/Icinga/Application/Modules/Manager.php(583): Icinga\Application\Libraries->has()
#3 /usr/share/icingaweb2/application/views/scripts/config/module.phtml(13): Icinga\Application\Modules\Manager->hasUnmetDependencies()
#4 /usr/share/php/Icinga/Web/View.php(235): include(String)
#5 /usr/share/icingaweb2/library/vendor/Zend/View/Abstract.php(877): Icinga\Web\View->_run()
#6 /usr/share/icingaweb2/library/vendor/Zend/Controller/Action/Helper/ViewRenderer.php(904): Zend_View_Abstract->render()
#7 /usr/share/icingaweb2/library/vendor/Zend/Controller/Action/Helper/ViewRenderer.php(925): Zend_Controller_Action_Helper_ViewRenderer->renderScript()
#8 /usr/share/icingaweb2/library/vendor/Zend/Controller/Action/Helper/ViewRenderer.php(964): Zend_Controller_Action_Helper_ViewRenderer->render()
#9 /usr/share/icingaweb2/library/vendor/Zend/Controller/Action/HelperBroker.php(272): Zend_Controller_Action_Helper_ViewRenderer->postDispatch()
#10 /usr/share/icingaweb2/library/vendor/Zend/Controller/Action.php(518): Zend_Controller_Action_HelperBroker->notifyPostDispatch()
#11 /usr/share/php/Icinga/Web/Controller/Dispatcher.php(76): Zend_Controller_Action->dispatch()
#12 /usr/share/icingaweb2/library/vendor/Zend/Controller/Front.php(937): Icinga\Web\Controller\Dispatcher->dispatch()
#13 /usr/share/php/Icinga/Application/Web.php(304): Zend_Controller_Front->dispatch()
#14 /usr/share/php/Icinga/Application/webrouter.php(109): Icinga\Application\Web->dispatch()
#15 /usr/share/icingaweb2/public/index.php(4): require_once(String)
#16 {main}

This exception points to a condition inside Libraries.php. The elseif clause just assumes every name has at least one slash without testing for it.

    public function get($name)
    {
        $candidate = null;
        foreach ($this->libraries as $library) {
            $libraryName = $library->getName();
            if ($libraryName === $name) {
                return $library;
            } elseif (explode('/', $libraryName)[1] === $name) {
                // Also return libs which only partially match
                $candidate = $library;
            }
        }

        return $candidate;
    }

If I change the name of my library to have at least one slash inside its name, then the exception is gone.

To Reproduce

1. Go to /etc/httpd/conf.d/icingaweb2.conf and change the libdir like this:
   SetEnv ICINGAWEB_LIBDIR "/usr/share/icinga-php:/usr/share/icingaweb2/modules/libraries".
   ( I know this is not 100% clean, because its inside the module path, but it was working so far)
2. Reload Apache Service
3. Create your own library inside the non-default path and in the composer.json give it a name not containing any slash.
4. In IcingaWeb, navigate to configuration->module and click any module, which is having dependencies for libraries. E.g.: icingadb or vspheredb

Expected behavior

Don't throw exception when names of libraries not contain a slash

Screenshots

Your Environment

Include as many relevant details about the environment you experienced the problem in

• Icinga Web 2 version and modules (System - About): 2.9.6
• Web browser used: Chromium (108.0.5359.125)
• Icinga 2 version used (icinga2 --version): 2.13.6
• PHP version used (php --version): 7.3.33
• Server operating system and version: RHEL 7.9

Additional context