Respect response content type during JSON parsing

[Lakes41]

Difficulty: Hard

Type: Bug

Summary

Improve HTTP response parsing so non-JSON responses produce clearer errors instead of generic JSON parsing failures.

Current Behaviour

Successful responses are parsed with response.json() unless the status is 204, 205, or the content length is 0. Error responses also attempt JSON parsing and silently fall back to null when parsing fails.

Expected Behaviour

The SDK should inspect response Content-Type and produce clearer errors when an endpoint returns HTML, plain text, or malformed JSON unexpectedly.

Suggested Implementation

Add a response parsing helper that checks Content-Type. For expected JSON endpoints, parse JSON when content type includes application/json; otherwise throw a GuildPassError with INVALID_RESPONSE and safe metadata. Preserve current support for empty successful responses.

Files or Areas Likely Affected

• src/http/httpClient.ts
• src/errors/errorCodes.ts
• tests/httpClient.test.ts
• docs/sdk-guide.md

Acceptance Criteria

• Successful non-empty JSON responses still parse correctly
• Empty 204 and 205 responses remain supported
• HTML or plain-text success responses produce a clear invalid response error
• Malformed JSON produces a clear invalid response error
• Error responses with non-JSON bodies still produce safe GuildPassError values
• Tests cover JSON, empty, non-JSON, and malformed responses

Additional Notes

Do not include full raw response bodies in errors by default, as backend responses may contain sensitive details.

[shinzoxD]

Hi maintainers, I would like to take this issue if it is available.

I would add a focused response parsing helper in src/http/httpClient.ts that preserves the existing empty-response handling for 204/205/zero-length responses, parses JSON only when the content type is JSON-compatible, and throws a sanitized GuildPassError with INVALID_RESPONSE for HTML/plain-text or malformed JSON success responses. I would also keep non-JSON error responses mapped to safe GuildPassError values without including raw response bodies by default.

I would cover JSON, empty, non-JSON, malformed JSON, and non-JSON error response cases in tests/httpClient.test.ts, then update the SDK guide with the error behavior.

I will wait for assignment or GrantFox confirmation before opening a PR.

[JesseJohn7]

Hello Maintainer, I’ve reviewed the issue description and I’m confident I can work on it effectively. Please assign it to me.