Make logging more clear when indirect asset references cannot be loaded

[Laupetin]

Currently logging for "assets not being found" does not differ between indirect asset references and normal assets dependencies.
In both cases something along the following would be logged:
`Failed to load asset of type "xanim": "viewmodel_mp5_idle"``

For a user it is not really possible to know that in case of indirect asset references this is more like a warning and for asset dependencies it is fatal.
So the logging message for indirect asset references should differ and make clear this is not a fatal error.