CollectionSystemManager: Fix possible crash in destructor
CollectionSystemManager: Fix possible crash in destructor

This could happen if no mCustomCollectionsBundle was initialized.

joolswills/EmulationStation,jrassa/EmulationStation,joolswills/EmulationStation,jrassa/EmulationStation,joolswills/EmulationStation,jrassa/EmulationStation,jrassa/EmulationStation,joolswills/EmulationStation