fix synthetic anomaly datasets

[alexriedel1]

📝 Description

When using synthetic validation and test splits, the visualizer is broken.
This is because the path fort he synthetically generated anomalous samples is

anomalib/src/anomalib/data/utils/synthetic.py

Line 44 in 9a0c755

ROOT = "./.tmp/synthetic_anomaly"

The visualizes generates output file names by looking up the dataset name in this path but cannot find it and terminates before saving the visualizer images.

anomalib/src/anomalib/utils/path.py

Line 320 in 9a0c755

dataset_index = next(i for i, part in enumerate(input_path.parts) if part.lower() == dataset_name.lower())

To overcome this the dataset name is added o the temporary dir.

Also this error was obscured by wrong exception handling:

anomalib/src/anomalib/utils/path.py

Lines 319 to 323 in 9a0c755

	try:
	dataset_index = next(i for i, part in enumerate(input_path.parts) if part.lower() == dataset_name.lower())
	except ValueError:
	msg = f"Dataset name '{dataset_name}' not found in the input path."
	raise ValueError(msg) from None

will not catch the error because it is a StopIteration type error and not an ValueError.

The right task type for synthetic dataset needs to be set manually and cannot be used from the folder dataset

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[ashwinvaidya17]

Good catch