fix(importers): catch YAMLError instead of narrower ParserError in dataset v0 importer

[eschutho]

SUMMARY

ImportDatasetsCommand.validate() in superset/commands/dataset/importers/v0.py (the legacy/unversioned dataset importer) only caught yaml.parser.ParserError, missing sibling exceptions under yaml.error.YAMLError (ScannerError, ComposerError, ReaderError, ConstructorError). A raw error from these classes propagated as an unhandled 500 instead of the intended IncorrectVersionError → (after the dispatcher exhausts all import versions) CommandInvalidError (422) with a clear message. This is the same bug class fixed in #42366, #42401, and #42426 — #42426 fixed the identical narrow-catch pattern in the sibling v1 importer (superset/commands/importers/v1/utils.py's load_yaml()) and explicitly flagged this v0 site as the same pattern but out of scope for that PR. This PR closes that gap.

PROBLEM

ImportDatasetsCommand.validate() parses every file in a dataset import as YAML:

try:
    config = yaml.safe_load(content)
except yaml.parser.ParserError as ex:
    logger.exception("Invalid YAML file")
    raise IncorrectVersionError(
        f"{file_name} is not a valid YAML file"
    ) from ex

yaml.parser.ParserError, yaml.scanner.ScannerError, yaml.composer.ComposerError, etc. are siblings — all subclasses of yaml.error.YAMLError, not of each other (confirmed via yaml.parser.ParserError.__mro__). For example, yaml.safe_load('key: "unterminated string') raises yaml.scanner.ScannerError, which is not caught here.

This is reachable end-to-end: this v0 ImportDatasetsCommand is the last entry in superset/commands/dataset/importers/dispatcher.py's fallback list, reached whenever the v1 importer raises IncorrectVersionError (i.e. exactly the unversioned/legacy export format this v0 path exists to handle). If validate() leaks a raw ScannerError/etc., it propagates through run(), through the dispatcher's own generic except Exception: logger.exception(...); raise (which logs and re-raises, doesn't swallow it), and out through superset/datasets/api.py's import_ endpoint (POST /api/v1/dataset/import/), which has no try/except around command.run() — only Flask-AppBuilder's @safe decorator, turning it into an opaque generic 500. The same path is also reachable via the legacy_import_datasources CLI command. So importing a legacy-format dataset YAML file malformed in a way other than a ParserError currently 500s instead of surfacing a proper validation error.

FIX

Widen the except clause in validate() to except yaml.YAMLError as ex:. No other exception handling in this file was touched (this is the only yaml. try/except in v0.py). No behavior change for the already-working ParserError case; new coverage for ScannerError/ComposerError/ReaderError/ConstructorError.

TESTING INSTRUCTIONS

• Added two tests to tests/unit_tests/datasets/commands/importers/v0/import_test.py:
  • test_validate_parser_error_raises_incorrect_version_error — confirms the existing ParserError path ("[1, 2") still raises IncorrectVersionError, unchanged.
  • test_validate_scanner_error_raises_incorrect_version_error — confirms a ScannerError-triggering input ('key: "unterminated string') is now also caught and raises IncorrectVersionError, instead of leaking the raw yaml.scanner.ScannerError.
• Verified the new ScannerError test fails on pre-fix code (raw yaml.scanner.ScannerError propagates uncaught) and passes after the fix.
• Ran the full test file — all 5 tests pass (3 pre-existing + 2 new), no regressions.
• Ran ruff check, ruff format --check, and mypy on both changed files — no new issues.

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[bito-code-review]

Code Review Agent Run #b42831

Actionable Suggestions - 0

Review Details

• Files reviewed - 2 · Commit Range: 7dd7d14..7dd7d14

  • superset/commands/dataset/importers/v0.py
  • tests/unit_tests/datasets/commands/importers/v0/import_test.py
• Files skipped - 0
• Tools

  • MyPy (Static Code Analysis) - ✔︎ Successful
  • Astral Ruff (Static Code Analysis) - ✔︎ Successful
  • Whispers (Secret Scanner) - ✔︎ Successful
  • Detect-secrets (Secret Scanner) - ✔︎ Successful

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[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 65.23%. Comparing base (ba0900d) to head (7dd7d14).

Files with missing lines	Patch %	Lines
superset/commands/dataset/importers/v0.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #42442      +/-   ##
==========================================
- Coverage   65.23%   65.23%   -0.01%     
==========================================
  Files        2795     2795              
  Lines      157694   157694              
  Branches    36067    36067              
==========================================
- Hits       102871   102868       -3     
- Misses      52847    52849       +2     
- Partials     1976     1977       +1     

Flag	Coverage Δ
hive	38.39% <0.00%> (ø)
mysql	57.56% <0.00%> (ø)
postgres	57.60% <0.00%> (-0.01%)	⬇️
presto	40.31% <0.00%> (ø)
python	59.00% <0.00%> (-0.01%)	⬇️
sqlite	57.23% <0.00%> (ø)
unit	100.00% <ø> (ø)

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