Fix RandGridDistortiond converting entire dict when transform is skipped

[AlexanderSanin]

Summary

Fixes #8604

When _do_transform is False (transform randomly skipped), RandGridDistortiond called convert_to_tensor on the entire data dictionary. This converted non-image metadata values (integers, strings) into 0-dim tensors, causing AttributeError: 'int' object has no attribute 'numel' during DataLoader collation.

The fix only converts the transform's target keys (via self.key_iterator), consistent with how the transform processes keys in the normal code path.

Test plan

• Verify RandGridDistortiond with prob=0 no longer crashes in DataLoader with num_workers > 0
• Verify existing test_rand_grid_distortiond tests pass
• Verify non-image metadata in the dictionary is preserved as-is when the transform is skipped

Signed-off-by: Oleksandr Sanin alexaaander.sanin@gmail.com

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 22a09805-177b-4408-96da-a57e111b6fd3

📥 Commits

Reviewing files that changed from the base of the PR and between 37db0ad and 117d65b.

📒 Files selected for processing (1)

• monai/transforms/spatial/dictionary.py

🚧 Files skipped from review as they are similar to previous changes (1)

• monai/transforms/spatial/dictionary.py

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📝 Walkthrough

Walkthrough

This PR narrows many broad exception handlers from catching BaseException to catching Exception across module init, TF32 detection, auto3dseg processing, detection metrics, nnUNet runner, inferer, device config, and tests. It also fixes RandGridDistortiond’s skip-augmentation path to convert only selected keys in-place (resolving a DataLoader collation AttributeError).

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Out of Scope Changes check	⚠️ Warning	Most changes are exception handler narrowing (BaseException to Exception) across multiple files, unrelated to the core RandGridDistortiond fix described in the PR objective.	Remove or justify the exception handler changes in unrelated files (monai/init.py, data_analyzer.py, ensemble_builder.py, etc.); these should be separate PRs or documented if intentional.
Docstring Coverage	⚠️ Warning	Docstring coverage is 56.25% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	Title accurately describes the main fix: narrowing convert_to_tensor scope in RandGridDistortiond when transform is skipped.
Description check	✅ Passed	Description clearly explains the bug, root cause, the fix, and includes a test plan; follows the template structure with summary section.
Linked Issues check	✅ Passed	Changes directly address issue #8604: fix converts only transform target keys per self.key_iterator, preserving non-image metadata and preventing AttributeError during collation.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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