Runtime crash in Samformer initialization when metadata is None

[victorwon2001]

LLM generated content, by GPT-5.6 Sol

Reference Issues/PRs

Fixes #2212

What does this implement/fix? Explain your changes.

Samformer now validates metadata before base-model initialization and raises ValueError("metadata is required") when it is missing, matching the existing v2 model convention. The class docstring also documents that metadata is provided by EncoderDecoderTimeSeriesDataModule and lists the max_encoder_length, max_prediction_length, and encoder_cont keys consumed by Samformer.

What should a reviewer concentrate their feedback on?

• The early validation behavior for direct Samformer construction.
• The metadata documentation and focused regression test.

Did you add any tests for the change?

Yes. The focused metadata validation test and the Samformer v2 estimator suite pass, and pre-commit checks pass on the modified files.

Any other comments?

None.

PR checklist

• The PR title starts with either [ENH], [MNT], [DOC], or [BUG]. [BUG] - bugfix, [MNT] - CI, test framework, [ENH] - adding or improving code, [DOC] - writing or improving documentation or docstrings.
• Added/modified tests
• Used pre-commit hooks when committing to ensure that code is compliant with hooks. Install hooks with pre-commit install.
  To run hooks independent of commit, execute pre-commit run --all-files

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (main@67c354f). Learn more about missing BASE report.

Additional details and impacted files

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  Coverage        ?   88.20%           
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Flag	Coverage Δ
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pytest	88.20% <100.00%> (?)

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