fix: preserve HTTP status for non-JSON API errors

[mayankbohradev]

What

When the API (or a proxy/CDN in front of it) returns a non-JSON body, the SDK no longer always raises a fake 500 InternalServerError.

It now uses:

• the real HTTP status when status >= 400 (e.g. 429, 401, 503)
• 500 only when the status looks successful but the body still is not usable JSON

Applies to both request.py and async_request.py. Error type is application_error (aligned with the Node SDK’s non-JSON error path).

Why

HTTP clients already return (content, status_code, headers), but the request layer discarded status_code and hard-coded 500 whenever:

• Content-Type was not application/json, or
• json.loads failed

So a real rate-limit / unauthorized / gateway HTML page became an unhelpful internal server error. Callers could not branch on e.code or use retry-after from headers correctly.

JSON error payloads that include statusCode / name / message are unchanged (perform() still handles those).

Testing

• Added sync coverage in tests/request_test.py:
  • 429 + text/html → code == 429, headers preserved
  • 503 + non-JSON → code == 503
  • 200 + HTML → still code == 500
  • invalid JSON with 502 → code == 502
• Added async coverage for 401 + HTML
• Removed a vacuous emails_test case that patched make_request and never hit this path
• Local: pytest tests/request_test.py tests/emails_test.py (482 suite tests also green via tox -e py)
• Local: tox -e mypy green
• Note: local tox -e lint fails on Python 3.13 (flake8<5 + importlib_metadata); CI still runs lint on 3.8–3.11

Out of scope

Does not change behavior when a JSON body parses successfully but omits statusCode while the HTTP status is 4xx/5xx. That is a separate issue.

---

Summary by cubic

Preserves real HTTP status codes for non‑JSON API responses in both sync and async requests. Fixes false 500s so clients can react to 4xx/5xx correctly and use headers like Retry-After.

• Bug Fixes
  • Use actual HTTP status when the body isn’t JSON; fall back to 500 only if the status is <400 but the body is unusable.
  • Set error_type to "application_error" and preserve response headers on errors.
  • Updated resend/request.py and resend/async_request.py; added sync/async tests; removed a stale emails test.

^{Written for commit 8451c2d. Summary will update on new commits.}

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.96%. Comparing base (7f1acd0) to head (8451c2d).
⚠️ Report is 188 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #238       +/-   ##
===========================================
+ Coverage   82.66%   95.96%   +13.29%     
===========================================
  Files           4       61       +57     
  Lines          75     3221     +3146     
===========================================
+ Hits           62     3091     +3029     
- Misses         13      130      +117     

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