Adding explicit type cast and `class_exists()` check to `\core\Libraries::instance()`.
Adding explicit type cast and `class_exists()` check to `\core\Libraries::instance()`.

m4rcsch/li3_framework,SensCritique/lithium,SensCritique/lithium,davidpersson/lithium,jails/lithium,wbeater/lithium,datachand/lithium,mehlah/lithium,pixelcog/lithium,UnionOfRAD/lithium,mehlah/lithium,qoqa/lithium,m4rcsch/lithium-core-library,UnionOfRAD/lithium,graphis/lithium,wbeater/lithium,jails/lithium,m4rcsch/lithium-core-library,pixelcog/lithium,davidpersson/lithium,UnionOfRAD/framework,whowgames/lithium,datachand/lithium,whowgames/lithium,graphis/lithium,qoqa/lithium,muyehub/lithium,muyehub/lithium