fix: render degenerate judge histograms instead of raising (#905)

[chethanuk]

Summary

DatasetProfilerResults.to_report() raises on four judge-profile shapes that model_validate() accepts, so a schema-valid analysis result cannot be rendered. All four are one crash family on one render path (create_rich_histogram_table and its two callers), so they're fixed together.

Related Issue

Fixes #905
Closes #903

Changes

• create_rich_histogram_table (config/utils/visualization.py): max(data.values()) raised ValueError on an empty mapping, one line before the existing max_count <= 0 guard that already handled "nothing to draw". Changed to max(data.values(), default=0), and an empty mapping now renders a no data placeholder row instead of an empty table.
• create_judge_score_summary_table (config/analysis/utils/reporting.py): took a histogram by attribute (histogram.categories), so a MissingValue — which the field is typed to allow — raised AttributeError a frame earlier than the fix above. Parameter widened to CategoricalHistogramData | MissingValue; a MissingValue now builds an empty mapping instead.
• JudgeScoreProfilerResults.create_report_section (config/analysis/column_profilers.py): indexed self.score_distributions.histograms[score_name] unguarded, while score_distributions is itself typed ... | MissingValue — raising AttributeError when missing and KeyError when a summary names a score the histogram map omits. Both now fall back to MissingValue.CALCULATION_FAILED, which the guard above renders.
• Not touched: CategoricalHistogramData's list constraints. Adding min_length=1 would make CategoricalDistribution.from_series raise on an empty Series, which _load_stage_analysis catches and turns into None — trading a visible crash for a silently discarded analysis.

Testing

• Two parametrized tests added, driven through the public to_report() entry point both reporters used. On unmodified main with the tests applied: 5 failed, 58 passed — ValueError at visualization.py:265, AttributeError at reporting.py:174, AttributeError and KeyError at column_profilers.py:146, matching both issues verbatim.
• With the fix, same command: 63 passed.
• uv run --group dev pytest packages/data-designer-config/tests → 652 passed (main: 644; the +8 is exactly the new cases).
• uv run --group dev pytest packages/data-designer-engine/tests → 2257 passed.
• make check-all-fix clean, tree unmodified.

Checklist

• Follows commit message conventions
• Commits are signed off (DCO)
• Unit regression coverage added

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[greptile-apps]

Greptile Summary

This PR makes judge-profile reports render schema-valid empty or missing histogram states instead of raising exceptions.

• Normalizes missing score distributions and absent per-score histograms to an empty histogram.
• Makes histogram rendering safe for empty mappings and displays a “no data” placeholder.
• Adds regression coverage through the public report API and focused visualization tests.

Confidence Score: 5/5

The PR appears safe to merge and addresses the identified report-rendering failures without introducing a concrete regression.

The changed path consistently converts every supported missing-histogram representation into an empty mapping, while populated and all-zero histograms retain their existing rendering behavior.

Important Files Changed

Filename	Overview
packages/data-designer-config/src/data_designer/config/analysis/column_profilers.py	Safely resolves missing score distributions and absent per-score histograms before constructing report tables.
packages/data-designer-config/src/data_designer/config/analysis/utils/reporting.py	Accepts typed missing histogram values and normalizes them to empty renderable data.
packages/data-designer-config/src/data_designer/config/utils/visualization.py	Handles empty mappings without calling max() on an empty sequence and renders a placeholder row.
packages/data-designer-config/tests/config/analysis/test_dataset_profiler_results.py	Covers empty, missing, omitted, and populated judge histograms through the public report-writing path.
packages/data-designer-config/tests/config/utils/test_visualization.py	Verifies row and bar behavior for empty, all-zero, and populated histogram inputs.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart LR
    A[Judge profile results] --> B{Score distributions available?}
    B -- No --> C[MissingValue]
    B -- Yes --> D{Histogram exists for score?}
    D -- No --> C
    D -- Yes --> E[Categorical histogram]
    C --> F[Empty histogram mapping]
    E --> G[Category/count mapping]
    F --> H[Rich histogram table]
    G --> H
    H --> I[Rendered report section]

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[chethanuk]

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