bug: [v4] docs say errors in `onSuccess` are ignored, but it actually makes the task fail.

[cachho]

Provide environment information

vercel

Describe the bug

Reproduction repo

not at this moment

To reproduce

have a onSuccess in a task fail.

Additional information

No response

[matt-aitken]

I think we should catch errors in here and log them but still have the run succeed

[matt-aitken]

@claude can you take a look at this?

[claude]

Claude finished @matt-aitken's task in 3m 5s —— View job • claude/issue-2002-20260108-2131 • Create PR ➔

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Fix Implemented

• Read CLAUDE.md for repo-specific guidelines (not present)
• Find and understand the onSuccess lifecycle hook implementation
• Implement fix to log errors in onSuccess/onComplete/onFailure hooks
• Push the fix

Summary:

Modified packages/core/src/v3/workers/taskExecutor.ts to properly handle errors in lifecycle hooks (onSuccess, onFailure, onComplete):

1. Errors are now caught inside the span callback using tryCatch
2. Errors are recorded to the span using recordSpanException so they're visible in tracing
3. The task run still succeeds as documented (errors don't propagate)

This ensures users can see when their onSuccess hooks fail without the entire task failing, matching the documented behavior.

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