Screen is not updated, if host group deleted and appears error
Steps to reproduce:
1. Create host with two host groups
2. Create Triggers overview screen (or other where can select host group)
3. Select host group, save
4. Open screen view in another browser tab
5. Delete host group
6. Wait for screen update in another browser tab
Result:

array_key_exists() expects parameter 2 to be array, boolean given [jsrpc.php:182 ? CScreenBuilder::getScreen() ? array_key_exists() in include/classes/screens/CScreenBuilder.php:193]