* Fix misleading 'only for image models' error for Qwen3-VL when torchvision is missing
transformers >= 5.4 hard-requires torchvision for VLM image/video processors and
no longer falls back to a slow processor. Without torchvision the processor load
raises ImportError, unsloth degrades to a text-only tokenizer, and the vision data
collator later fails with 'UnslothVisionDataCollator is only for image models!'.
Detect this case at load time and raise a clear, actionable error pointing at the
missing torchvision dependency instead.
Fixesunslothai/unsloth#4202
* Apply kwarg-spacing format hook to vision torchvision guard (pre-commit)
* Make torchvision-missing detection precise: check availability first, match specific error text
* Tighten code comments (no logic change)
* Make missing-torchvision VLM error version-agnostic
The raise also fires on transformers 4.57.x for VLMs with a video processor
(Qwen2.5-VL, Qwen3-VL), where AutoVideoProcessor requires torchvision. The old
message claimed 'transformers >= 5.4 requires torchvision', which is inaccurate
on 4.57.x. Reword to state torchvision is required for this model's vision
processors without a version-specific claim.
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Co-authored-by: danielhanchen <michaelhan2050@gmail.com>
