[eslint-miner] eslint-factory: add require-error-code-for-fetch-throw rule #63813

Summary

Adds a new custom ESLint rule, require-error-code-for-fetch-throw, that flags throw new Error(...) following a bare fetch(...) call when the throw doesn't include a standardized error code (E###, ERR_*, SAFE_OUTPUT_E###) — even in files that have never imported error_codes.cjs.

Evidence

Two existing rules (require-error-code-in-thrown-error and require-error-code-for-github-api-throw) both gate on the file already importing ./error_codes.cjs — they never fire for files that haven't adopted the convention at all. This is a real, recurring gap:

• actions/setup/js/azure_devops_work_items.cjs has been repeatedly flagged by the Safe Outputs Conformance script's USE-001 check for missing standardized error codes across 5+ separate runs in the last 14 days: [Safe Outputs Conformance] USE-001: azure_devops_work_items.cjs missing standardized error codes #63370, [Safe Outputs Conformance] USE-001: azure_devops_work_items.cjs missing standardized error codes #61738, [Safe Outputs Conformance] USE-001: azure_devops_work_items.cjs missing standardized error codes #61965, [Safe Outputs Conformance] USE-001: azure_devops_work_items.cjs does not use standardized error codes #62136, [Safe Outputs Conformance] USE-001: azure_devops_work_items.cjs missing standardized error codes #62320, plus a fresh instance today ([Safe Outputs Conformance] USE-001: azure_devops_work_items.cjs missing standardized error codes #63790). It still has zero error-code tokens anywhere in the file despite making fetch() calls and throwing on failure (~55 throw new Error(...) sites).
• The same adoption gap exists in artifact_client.cjs (31 throws, 5 fetch() calls) and exchange_otlp_workload_identity.cjs (9 throws, 2 fetch() calls) — both call fetch() and throw Error(...) on failure, with no error code anywhere in either file.
• Files that already adopted the convention (linear_graphql.cjs, runtime_import.cjs, validate_secrets.cjs) are correctly left untouched by the new rule since they already reference ERR_*/E### codes at their throw sites.

Implementation

• New rule: eslint-factory/src/rules/require-error-code-for-fetch-throw.ts
  • Modeled on the existing require-error-code-for-github-api-throw rule's architecture: map bare fetch(...) call positions per enclosing function, then flag same-function throw new Error(...) statements lacking a code.
  • Detects only bare fetch(...) identifier calls (deliberately excludes member-expression calls like octokit.request(...) or transport.fetch(...), which are covered by the sibling GitHub-API rule or are wrapper abstractions) to avoid overlap/false positives.
  • Does not gate on error_codes.cjs being imported — that's the entire point of the rule: catching files that haven't adopted the convention yet.
  • Reuses the shared ERROR_CODE_PATTERN and resolveWriteOnceInitializerChain helpers for consistency with the sibling rule.
• Tests: eslint-factory/src/rules/require-error-code-for-fetch-throw.test.ts (6 cases): valid with error-code-suffixed message, valid with inline string-literal code, invalid throw after bare fetch with no code, valid throw with no preceding fetch, valid throw before the fetch call, valid member-expression fetch call not flagged, valid unrelated sibling-function fetch call not flagged.
• Registered in eslint-factory/src/index.ts and enabled ("warn") in eslint-factory/eslint.config.cjs for the actions/setup/js lint target.
• Documented in eslint-factory/README.md (TOC entry + detail section with flagged/safe examples).

Validation

• cd eslint-factory && npm install — succeeds.
• npm run build — passes, no type errors.
• npm test — 687/687 tests pass (67 files), including the README/rule-registry parity check.
• npm run lint:setup-js — exits 0 (all warnings, no errors); the new rule fires 22 times across exactly 3 real files (azure_devops_work_items.cjs, artifact_client.cjs, exchange_otlp_workload_identity.cjs), confirming it's high-signal and not noisy or duplicative of the two existing error-code rules.

Scope

Changes limited to eslint-factory/** (new rule + tests + registration + docs). No changes to actions/setup/js/** source files, Go code, or documentation outside eslint-factory.

To route changes like this to a review issue instead of blocking, configure protected-files: fallback-to-issue in your workflow configuration.

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• expires on Oct 4, 2026, 1:01 AM UTC-08:00