Fix VAEDecodeTiled crash on NestedTensor latents (MiniMax H3) (#15477)

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.

tests-unit/comfy_test/test_vae_decode_tiled_nested.py

@@ -0,0 +1,27 @@
+from unittest.mock import MagicMock
+
+import torch
+
+from comfy.cli_args import args as cli_args
+
+if not torch.cuda.is_available():
+    cli_args.cpu = True
+
+import comfy.nested_tensor  # noqa: E402
+import nodes  # noqa: E402
+
+
+def test_vae_decode_tiled_unwraps_nested_tensor():
+    video = torch.zeros(1, 4, 2, 8, 8)
+    audio = torch.zeros(1, 2, 2, 40)
+    samples = {"samples": comfy.nested_tensor.NestedTensor((video, audio))}
+
+    vae = MagicMock()
+    vae.temporal_compression_decode.return_value = None
+    vae.spacial_compression_decode.return_value = 8
+    vae.decode_tiled.return_value = torch.zeros(1, 3, 2, 8, 8)
+
+    nodes.VAEDecodeTiled().decode(vae, samples, tile_size=512)
+
+    decoded_arg = vae.decode_tiled.call_args[0][0]
+    assert decoded_arg is video