feat(ai-ollama): enhance error handling in chatStream to emit RUN_ERROR events

[harshlocham]

• Added error handling in the OllamaTextAdapter's chatStream method to yield RUN_ERROR events instead of throwing errors directly.
• Introduced utility functions to format error payloads and raw events for better error reporting.
• Added a new test suite to verify the correct emission of RUN_ERROR events on chat stream rejections.

🎯 Changes

✅ Checklist

• I have followed the steps in the Contributing guide.
• I have tested this code locally with pnpm run test:pr.

🚀 Release Impact

• This change affects published code, and I have generated a changeset.
• This change is docs/CI/dev-only (no release).

Summary by CodeRabbit

• Bug Fixes
  • Improved error handling in Ollama chat streaming so failures now return a structured error event instead of throwing.
  • Included clearer error details, such as message, code, and available raw event data, to help surface stream failures consistently.
• Tests
  • Added coverage for rejected chat requests to confirm a single error event is emitted and no exception is thrown.

[coderabbitai]

📝 Walkthrough

Walkthrough

OllamaTextAdapter.chatStream now imports toRunErrorPayload and toRunErrorRawEvent from @tanstack/ai/adapter-internals. The catch block no longer rethrows; it builds a structured RUN_ERROR chunk and yields it to the stream. A new test verifies this behavior on upstream rejection.

Ollama chatStream RUN_ERROR emission

Layer / File(s)	Summary
chatStream error handling and test packages/ai-ollama/src/adapters/text.ts, packages/ai-ollama/tests/text-adapter.test.ts	Imports toRunErrorPayload/toRunErrorRawEvent; replaces rethrow with a RUN_ERROR chunk yield containing message, code, optional rawEvent, and an error object. Test mocks a pre-stream rejection and asserts the single emitted chunk type and message.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related PRs

• TanStack/ai#673: Applies the same toRunErrorRawEvent/RUN_ERROR enrichment pattern that this PR now adds to the Ollama adapter's error path.

Suggested reviewers

• AlemTuzlak

🐇 A stream once crashed and threw a fit,
now errors land soft, yielded bit by bit.
RUN_ERROR hops along with grace,
rawEvent tucked in its little place.
No more rethrows — just a tidy chunk! 🎉

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is specific and accurately summarizes the main change: Ollama chatStream now emits RUN_ERROR events on failures.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description check	✅ Passed	The PR description matches the required template and includes the change summary, checklist, and release impact.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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