VAEDecode unwraps a NestedTensor latent (video/audio pair) to its
video component before calling vae.decode(). VAEDecodeTiled skipped
this unwrap and passed the NestedTensor straight into
vae.decode_tiled(), which fails deep in the MiniMax H3 video VAE when
a real tensor's .to() is called with the NestedTensor as an argument.
Fixes#15468.
chelsealong