fix: Include the last data source error in the provider error event

[kinyoklion]

The PROVIDER_ERROR event now carries the last data source error instead of a fixed "Provider shutdown" message.

• Matches the OFP spec, which requires the error event to report the last data source error, with a description as a fallback
• Matches the PROVIDER_STALE branch, which already reports the last error, and the wording used by the Python provider

Implementation details

Found during the weekly OpenFeature provider audit against launchdarkly/sdk-specs (OFP).

handleDataSourceStatus discarded res.getLastError() in the OFF case, so an application listening for PROVIDER_ERROR had no way to see why the data source permanently failed (for example a 401 from an invalid SDK key). The state transition and initialization behavior are unchanged.

The message is ErrorInfo.toString(), not ErrorInfo.getMessage(): ErrorInfo.fromHttpError leaves the message null and records the failure as a kind plus a status code, so getMessage() would emit a null message for exactly the HTTP failures this change is meant to surface. toString() is the SDK's own rendering of the kind, status code, and message.

Requirements

• I have added test coverage for new or changed functionality
• I have followed the repository's pull request submission guidelines
• I have validated my changes against all supported platform versions

Related issues

None.

Describe alternatives you've considered

Keeping the static message and adding the error as event metadata: OpenFeature only exposes a message on the event details, so the message is the right place for it.

Testing

./gradlew test checkstyleMain. Lifecycle tests cover a data source that fails after initialization with a kind/status/message error, and one that fails with an HTTP-only error, asserting the emitted message is non-empty and names the status code.

Link to Devin session: https://app.devin.ai/sessions/38a6eaf69fcf41109e136a1d0fe5e899
Open in Devin Desktop: https://app.devin.ai/desktop/session/38a6eaf69fcf41109e136a1d0fe5e899?variant=devin
Requested by: @kinyoklion

[devin-ai-integration]

🤖 Devin AI Engineer

I'll be helping with this pull request! Here's what you should know:

✅ I will automatically:

• Address comments on this PR. Add '(aside)' to your comment to have me ignore it.
• Look at CI failures and help fix them

Note: I can only respond to comments from users who have write access to this repository.

⚙️ Control Options:

• Disable automatic comment, CI, and merge conflict monitoring

[devin-ai-integration]

@cursor review

[cursor]

Cursor Bugbot has reviewed your changes using default effort and found 1 potential issue.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, have a team admin enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit dd39f2c. Configure here.}