fix(core): sort channels with disposed state last instead of crashing

[testableapple]

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Linear: FLU-692

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• Code changes are tested (add some information if not applicable)

Description of the pull request

StreamChannelListController's value setter sorts the page locally whenever a channelStateSort is active (including when a predefinedFilter resolves an effectiveSort), using a null assert on the channel state:

(it) => it.state!.channelState,

Channel.dispose() nulls state, so an in-flight doInitialLoad/loadMore that resumes after channels were disposed — a logout/disconnect racing an in-flight pagination, or a channel removed by a deleted/hidden event while a query is in flight — crashes with Null check operator used on a null value. Caught by the nightly e2e run (iOS 18.5, channel_list_test.dart), where the teardown's client.dispose() raced a scroll-triggered loadMore.

The sort key is now it.state?.channelState with a nulls-last comparator, so disposed channels sort to the end instead of crashing. No further lifecycle guards are needed: the base PagedValueNotifier already discards value writes after the controller itself is disposed.

Testing: added a regression test (fails with a null-check _TypeError on the unfixed code) that mixes a state-less channel into a sorted page and asserts it lands last while live channels keep the sort order.

Summary by CodeRabbit

• Bug Fixes
  • Fixed channel list sorting during in-flight queries when a channel has been disposed.
  • Disposed or unavailable-state channels are now placed after active channels instead of causing an error.
  • Active channels continue to follow the configured sorting order.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 5f7f35b2-6652-42d1-be66-2ccb3381a416

📥 Commits

Reviewing files that changed from the base of the PR and between 02ba6a2 and 2f41b78.

📒 Files selected for processing (3)

• packages/stream_chat_flutter_core/CHANGELOG.md
• packages/stream_chat_flutter_core/lib/src/stream_channel_list_controller.dart
• packages/stream_chat_flutter_core/test/stream_channel_list_controller_test.dart

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📝 Walkthrough

Walkthrough

StreamChannelListController now sorts channels with null state safely. Disposed channels sort last, while active channels continue using the configured comparator. A regression test and changelog entry document the fix.

Changes

Channel sorting

Layer / File(s)	Summary
Null-state sorting behavior packages/stream_chat_flutter_core/lib/src/stream_channel_list_controller.dart, packages/stream_chat_flutter_core/test/stream_channel_list_controller_test.dart, packages/stream_chat_flutter_core/CHANGELOG.md	The controller handles null channel states without a null assertion. Active channels use the configured comparator, disposed channels sort last, and regression coverage verifies the ordering. The changelog records the fix.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to 2f41b

This localized change makes disposed channels sort last instead of causing a crash, with a regression test covering the behavior. No actionable merge-blocking risk remains beyond normal checks and review.

Suggested reviewers: velikovpetar, xsahil03x

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the fix for sorting channels with disposed state without a crash.
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.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch alexeyalterpesotskiy/flu-692-streamchannellistcontroller-local-sort-crashes-on-channels

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.96%. Comparing base (09a918b) to head (37e9b83).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2887   +/-   ##
=======================================
  Coverage   73.96%   73.96%           
=======================================
  Files         435      435           
  Lines       28147    28149    +2     
=======================================
+ Hits        20818    20821    +3     
+ Misses       7329     7328    -1     

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