Module Channel Configuration: No Available Channels results in Stack Trace for Add Channel

[oxzi]

An empty available_channel_type table results in a stack trace when one tries to add a new channel. This might happen if the daemon was not started yet.

To reproduce, start with a "clean" database or optionally delete all entries from available_channel_type. Start your clicking journey in Icinga Web from the configuration gear in the sidebar, go to Modules, select the notifications module, go to the Channels tab and Add Channel.

Undefined array key ""

#0 /usr/share/icingaweb2-modules/notifications/application/forms/ChannelForm.php(103): Icinga\Application\ApplicationBootstrap->Icinga\Application\{closure}(Integer, String, String, Integer)
#1 /usr/local/src/ipl-html/src/HtmlDocument.php(344): Icinga\Module\Notifications\Forms\ChannelForm->assemble()
#2 /usr/local/src/ipl-html/src/Form.php(210): ipl\Html\HtmlDocument->ensureAssembled()
#3 /usr/share/icingaweb2-modules/notifications/application/controllers/ChannelsController.php(117): ipl\Html\Form->handleRequest(Object(GuzzleHttp\Psr7\ServerRequest))
#4 /usr/share/icinga-php/vendor/vendor/shardj/zf1-future/library/Zend/Controller/Action.php(522): Icinga\Module\Notifications\Controllers\ChannelsController->addAction()
#5 /icingaweb2/library/Icinga/Web/Controller/Dispatcher.php(76): Zend_Controller_Action->dispatch(String)
#6 /usr/share/icinga-php/vendor/vendor/shardj/zf1-future/library/Zend/Controller/Front.php(954): Icinga\Web\Controller\Dispatcher->dispatch(Object(Icinga\Web\Request), Object(Icinga\Web\Response))
#7 /icingaweb2/library/Icinga/Application/Web.php(294): Zend_Controller_Front->dispatch(Object(Icinga\Web\Request), Object(Icinga\Web\Response))
#8 /icingaweb2/library/Icinga/Application/webrouter.php(105): Icinga\Application\Web->dispatch()
#9 /icingaweb2/public/index.php(4): require_once(String)
#10 {main}