fix(ai): throw timeout error when streamText times out

[shubham-021]

Background

When streamText times out before generating any output, it throws a generic NoOutputGeneratedError with the message "No output generated. Check the stream for errors.". It should throw NoOutputGeneratedError with a proper timeout message and cause.

Summary

When abort occurs, the abort reason is used as error. It can be an AbortError or a TimeoutError (or a custom reason object).

Manual Verification

• run examples/ai-core/src/stream-text/openai-timeout.ts and verify output

Checklist

• Tests have been added / updated (for bug fixes / features)
• Documentation has been added / updated (for bug fixes / features)
• A patch changeset for relevant packages has been added (for bug fixes / features - run pnpm changeset in the project root)
• I have reviewed this pull request (self-review)

Related Issues

fixes #11577

[lgrammel]

Thanks! The behavior should match generateText:

❯ pnpm tsx src/generate-text/openai-timeout
DOMException [TimeoutError]: The operation was aborted due to timeout

You can verify by running

~/repositories/ai/examples/ai-core main *46 ··································· 11:08:57
❯ pnpm tsx src/stream-text/openai-timeout

[shubham-021]

Thanks! The behavior should match generateText:

❯ pnpm tsx src/generate-text/openai-timeout
DOMException [TimeoutError]: The operation was aborted due to timeout

You can verify by running

~/repositories/ai/examples/ai-core main *46 ··································· 11:08:57
❯ pnpm tsx src/stream-text/openai-timeout

I think this well aligned now

pnpm tsx src/stream-text/openai-timeout
DOMException [TimeoutError]: The operation was aborted due to timeout

[lgrammel]

using timeouts in tests is not recommended. it slows down test exection.

can this be solved with fake timers (vi faketimers)?

[shubham-021]

i tried using faketimer , but it is not simulating the blocker perfectly , giving test timeout.
Can you help me here , what i initially thought was we can plant a promise inside doStream method which doesnt resolve and then advance the timer with more than timeout time , but that gives a test timeout.