fix(query-core): handle combine throwing in QueriesObserver notify

[veeceey]

Fixes #10129

When useSuspenseQueries is used with combine, the types narrow data to always be defined. But if a query transitions back to pending/error state (e.g. via queryClient.resetQueries()), the combine function gets called with results where data is undefined, causing a runtime TypeError.

This happens because QueriesObserver.#notify() calls combine as an optimization check — to see if the combined result changed before notifying listeners. The listeners themselves receive raw results (not the combined one), so the combine call is purely for deduplication.

The fix wraps the combine call in a try/catch. If combine throws, we treat it as a change and notify listeners anyway. This lets the framework-level code (React Suspense / Error Boundary) handle the state transition properly.

Added a test that reproduces the exact scenario: subscribe to a QueriesObserver with a combine function that accesses data properties, let queries resolve, then call resetQueries — previously this would throw, now it correctly notifies listeners with the pending result.

Summary by CodeRabbit

• Bug Fixes

  • Improved observation notification so listeners are reliably notified even if a data-combining step throws.

• Tests

  • Added test coverage for notification behavior during query resets and error scenarios (duplicate test entry present).

• Chores

  • Added a changeset documenting the fix and bumping the patch version.

[changeset-bot]

🦋 Changeset detected

Latest commit: 2caed00

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 22 packages

Name	Type
@tanstack/query-core	Patch
@tanstack/angular-query-experimental	Patch
@tanstack/preact-query	Patch
@tanstack/query-async-storage-persister	Patch
@tanstack/query-broadcast-client-experimental	Patch
@tanstack/query-persist-client-core	Patch
@tanstack/query-sync-storage-persister	Patch
@tanstack/react-query	Patch
@tanstack/solid-query	Patch
@tanstack/svelte-query	Patch
@tanstack/vue-query	Patch
@tanstack/angular-query-persist-client	Patch
@tanstack/preact-query-devtools	Patch
@tanstack/preact-query-persist-client	Patch
@tanstack/react-query-persist-client	Patch
@tanstack/solid-query-persist-client	Patch
@tanstack/svelte-query-persist-client	Patch
@tanstack/react-query-devtools	Patch
@tanstack/react-query-next-experimental	Patch
@tanstack/solid-query-devtools	Patch
@tanstack/svelte-query-devtools	Patch
@tanstack/vue-query-devtools	Patch

Not sure what this means? Click here to learn what changesets are.

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: b904770c-fc04-481b-b748-7561513185c8

📥 Commits

Reviewing files that changed from the base of the PR and between ab3e122 and 2caed00.

📒 Files selected for processing (3)

• .changeset/brave-tigers-wave.md
• packages/query-core/src/__tests__/queriesObserver.test.tsx
• packages/query-core/src/queriesObserver.ts

🚧 Files skipped from review as they are similar to previous changes (1)

• packages/query-core/src/queriesObserver.ts

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📝 Walkthrough

Walkthrough

Adds guarded notification logic to QueriesObserver.notify so combine() errors don't prevent listener notifications. Includes a test asserting listeners are notified with pending status and undefined data when combine throws after a query reset, and a changeset recording the fix.

Changes

Cohort / File(s)	Summary
Core Implementation packages/query-core/src/queriesObserver.ts	Wraps the combine/newResult computation in a try/catch, introduces a shouldNotify fallback when combine throws, and preserves tracking and result update flow so listeners are still notified even if combine errors.
Test Coverage packages/query-core/src/__tests__/queriesObserver.test.tsx	Adds a test "should still notify listeners when combine throws after query reset" that verifies a listener receives a pending status with undefined data after a reset that causes combine to throw.
Release Metadata .changeset/brave-tigers-wave.md	Adds a changeset patch noting the fix: "handle combine throwing in QueriesObserver notify".

Sequence Diagram(s)

mermaid
sequenceDiagram
participant Subscriber
participant QueriesObserver
participant QuerySet
Subscriber->>QueriesObserver: subscribe()
QueriesObserver->>QuerySet: read latest query results
QuerySet-->>QueriesObserver: results (may include pending/error)
alt combine succeeds
QueriesObserver->>QueriesObserver: compute newResult = combine(results)
QueriesObserver->>Subscriber: notify(newResult)
else combine throws
QueriesObserver->>QueriesObserver: catch error
QueriesObserver->>Subscriber: notify(fallback pending/undefined result)
end

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Suggested reviewers

• TkDodo

Poem

🐰 I stitched a gentle, watchful thread,
So falls from combine won't cloud what's said.
Listeners still prick their eager ears,
Even when queries stall with fears.
Hoppity hops — error handled, cheer! 🥕

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'fix(query-core): handle combine throwing in QueriesObserver notify' accurately and concisely summarizes the main fix in the changeset.
Description check	✅ Passed	The PR description clearly explains the problem, fix, rationale, and testing approach. The checklist template was provided but completion status is not required for this assessment.
Linked Issues check	✅ Passed	The changes successfully address #10129 by wrapping the combine call in a try/catch block, allowing listeners to be notified even when combine throws, which handles pending/error state transitions.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to fixing the reported issue: error handling in QueriesObserver.notify, a corresponding test, and a changeset entry.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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