Dial back our exception throwing usage in non-critical scenarios (introduce default resources when we fail to load assets)

[Kejoko]

We do not need to be throwing exceptions as liberally as we do currently.

If we do not load a texture or image correctly, we should introduce a default image / texture to use instead. We should report an error, but this is not critical and we should not throw.

If we do not load a model or mesh correctly, we should introduce a default model / mesh to use instead. We should report an error, but this is not critical and we should not throw.