fix(api): surface server error message instead of generic 'API request failed'

[mohn93]

Summary

Fixes a reported issue: API error logs/exceptions showed a generic "API request failed" instead of the server's actual error.

A dev hit a 400 on update-subscriber whose body was:

{ "errors": [ { "path": "data.phone", "message": "Phone is required" } ] }

…but the SDK logged HTTP 400 msg="API request failed". Root cause: the error parser only read a top-level message/error string, so the nested errors[].message shape fell through to the hardcoded default.

Change

_handleResponse error-message resolution is now a fallback chain:

1. top-level message
2. top-level error
3. errors[].message (joined with ; for multiple) ← fixes the reported case
4. the whole raw response body ← replaces the generic "API request failed"
5. only if the body is empty/blank → "API request failed with status <n>"

Also handles non-JSON bodies (e.g. an HTML gateway page) by surfacing them raw. The full body was — and still is — available on PushFireApiException.responseBody; this just makes .message and the log line useful too.

Per team decision, the raw-body fallback is untruncated (consistent with the existing raw/no-truncation logging stance); responseBody keeps the full body regardless.

Tests

Added to test/api/pushfire_api_client_test.dart:

• nested errors[] → surfaces "Phone is required"
• multiple errors[] → joined
• unknown JSON object shape → whole body
• non-JSON body → surfaced raw
• empty body → status fallback

Full suite: 371 passing, flutter analyze clean.

Released as 0.2.1.

🤖 Generated with Claude Code