Attach TurboModule identity to exceptions rethrown from async and void calls (#58264)

[christophpurrer]

Summary:

When an ObjC TurboModule method raises an NSException, what happens next depends on how it was
called. A sync call converts it into a JSError via convertNSExceptionToJSError, which builds
<module>.<method> raised an exception: <reason>. The async and void paths cannot do that — they
run on the module's method queue with no JS runtime to attach the error to — so they rethrow.

Both rethrow sites discarded moduleName and methodNameStr, even though both are captured in the
enclosing block and in scope at the throw site. Because void and async methods are dispatched onto
the method queue, the rethrown exception is uncaught and terminates the process, and by then every
module frame has unwound: the reported stack bottoms out in objc_exception_rethrow followed by a
libdispatch queue drain. Nothing in the resulting crash says which module or method failed.

The practical effect is that all such crashes — regardless of which module raised them, and
regardless of whether the underlying bug is a null argument, a wrong-typed argument, or anything
else — collapse into a single crash bucket with no owner attached, and cannot be split or routed.

This adds an addModuleIdentityToException helper next to convertNSExceptionToJSError and applies
it at both rethrow sites. It preserves the exception's name and its existing userInfo entries so
any predicate-based handling is unaffected, and prefixes reason with <module>.<method> to match
the sync path's wording. A freshly constructed NSException captures its call stack at throw
rather than at the original raise, so the raise-site return addresses are carried across in
userInfo and nothing is lost.

Behaviour is otherwise unchanged: the exception is still thrown, on the same thread, at the same
point, with the same name. Nothing is caught, swallowed, logged away, or downgraded.

Reviewers should expect the crash grouping to change: the existing aggregate bucket will drain and
be replaced by per-module buckets. That is the point of the change, but it is worth knowing before
it happens.

Changelog:
[iOS][Fixed] - Include the module and method name in exceptions rethrown from async and void TurboModule calls

Differential Revision: D118144605

[meta-codesync]

@christophpurrer has exported this pull request. If you are a Meta employee, you can view the originating Diff in D118144605.

[Abbondanzo]

/review

[github-actions]

🤖 AI code review

Decision: Ready for human review

Overall PR risk: Low. Change modifies existing behavior in the iOS ObjC TurboModule async and void NSException rethrow path to include module and method identity in the rethrown exception. Blast radius is limited to iOS diagnostics with no JS/Android or public API change, and rollback is a single-file revert. Most plausible breakage is crash grouping or log parsers that expect the prior exact reason string or do not expect the new userInfo key; no warning or critical findings were reported.

No findings.

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This review is advisory — it never blocks a merge and never auto-approves.