fix: surface output.postProcess execution errors

[Copilot]

• Fix postprocessOutput in packages/shared/src/config/output/postprocess.ts to check result from sync() and throw meaningful errors when:
  • result.error is set (e.g., ENOENT when command is not found in PATH)
  • result.status is non-zero (command exited with failure), including stderr in the message
• Refactor non-zero status error message to use let to avoid duplicating the base message string
• Add unit tests in packages/shared/src/config/output/__tests__/postprocess.test.ts covering the new error-handling behavior (10 new tests, all passing)
• Run lint and tests to verify changes (all tests pass, lint clean)

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[pullfrog]

Reviewed PR #3683 — it's a WIP draft with zero code changes (the only commit is an empty "Initial plan" commit). No code to review yet; will re-review once implementation commits are pushed.

  ^{｜ View workflow run ｜ Triggered by Pullfrog ｜ 𝕏}

[changeset-bot]

🦋 Changeset detected

Latest commit: df406de

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@hey-api/openapi-ts	Patch
@hey-api/shared	Patch
@hey-api/openapi-python	Patch

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Project	Deployment	Actions	Updated (UTC)
hey-api-docs	Ready	Preview, Comment	Apr 3, 2026 6:35pm

[mrlubos]

@copilot avoid duplicating hard-coded message string for non-zero status codes, use let instead of const to avoid duplication

[Copilot]

@copilot avoid duplicating hard-coded message string for non-zero status codes, use let instead of const to avoid duplication

Done in 329d983 — refactored to use let so the base message is built once and stderr is conditionally appended.

[pullfrog]

Reviewed PR #3683. The core error detection logic is correct and tests are thorough. Flagged two issues: (1) throwing plain Error instead of ConfigError causes crash report + GitHub issue prompt for what is a user configuration problem, and (2) a minor edge case where signal-killed processes produce a confusing "exited with code null" message.

Task list (4/4 completed)

• Read the PR diff to understand changes
• Read the full source files for context
• Review linked issue for context
• Draft and submit review

  ^{｜ View workflow run ｜ Triggered by Pullfrog ｜ 𝕏}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 39.47%. Comparing base (549a42e) to head (df406de).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3683      +/-   ##
==========================================
+ Coverage   39.39%   39.47%   +0.07%     
==========================================
  Files         520      521       +1     
  Lines       19279    19299      +20     
  Branches     5708     5722      +14     
==========================================
+ Hits         7595     7618      +23     
+ Misses       9445     9442       -3     
  Partials     2239     2239              

Flag	Coverage Δ
unittests	39.47% <100.00%> (+0.07%)	⬆️

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[pullfrog]

TL;DR — postprocessOutput silently discarded spawn failures and non-zero exit codes from user-configured post-processors (e.g. prettier, biome). This PR captures the cross-spawn result and throws descriptive errors so users actually see what went wrong.

Key changes

• Add error handling to postprocessOutput — checks result.error (spawn failure) and result.status (non-zero exit), throwing with the processor name, exit code, and stderr when available.
• Add unit tests for postprocessOutput — 10 new tests covering happy paths, ENOENT spawn errors, non-zero exits with/without stderr, preset resolution, and fail-fast ordering.
• Add changeset — patch bump for @hey-api/openapi-ts and @hey-api/shared.

_{Summary ｜ 3 files ｜ 4 commits ｜ base: main ← copilot/fix-output-postprocess-error}

Error handling for post-processor execution

Before: sync() return value was ignored — a missing binary or a formatter crash produced no error, and generation appeared to succeed.
After: spawn failures throw Post-processor "<name>" failed to run: <message> and non-zero exits throw Post-processor "<name>" exited with code <N> with stderr appended when present.

The fix captures the cross-spawn sync() result and checks two conditions: result.error (set when the binary cannot be spawned at all, e.g. ENOENT) and result.status !== 0 (command ran but returned a failure code). A let-bound message string avoids duplicating the base text when appending stderr.

packages/shared/src/config/output/postprocess.ts · packages/shared/src/config/output/__tests__/postprocess.test.ts

  ^{｜ View workflow run ｜ Triggered by Pullfrog ｜ 𝕏}

[pullfrog]

The error detection logic is correct and the tests are thorough. Two issues worth addressing — one impacts user experience significantly, the other is a minor edge case.

  ^{｜ Fix all ➔ ｜ Fix 👍s ➔ ｜ View workflow run ｜ 𝕏}

[mrlubos]

@pullfrog implement your feedback. Also have a look at the failing CI, seems there was another bug lurking in the postprocessor implementation. Can you figure out how to fix that too?

[pullfrog]

Addressed all three review comments and fixed the CI failure. The review feedback (use ConfigError instead of Error, guard result.status !== null for signal-killed processes) is implemented. The CI bug was caused by post-processors (Oxfmt, ESLint) running against empty output directories — fixed by adding an early return in postprocessOutput when the directory doesn't exist or is empty. All 457 tests pass, lint and typecheck clean.

Task list (6/6 completed)

• Address review: use ConfigError instead of plain Error
• Address review: guard against null status (signal-killed processes)
• Fix CI: post-processor errors on empty output directories
• Update tests to match changes
• Build, lint, and test
• Commit, push, and reply to review comments

  ^{｜ View workflow run ｜ Triggered by Pullfrog ｜ 𝕏}