ChatFilters::applyRemove() emptied the filter in the list and only then
detached its chats. Unpinning a chat re-caches its siblings' pinned
indices, which runs Session::refreshChatListEntry(); seeing the filter
still listed but emptied, it re-entered removeFromChatList() ->
setChatPinned() -> PinnedList::setPinned() on the same pinned list while
its re-cache loop iterated with a cached size, reading past the end of
the vector. This aborted on closing the Folders editor after removing
two or more folders that had pinned chats.
Detach the filter from the list before applyChange() tears down its
chats, so the re-entrant refresh no longer touches it. Also harden the
setPinned() re-cache loop to re-check the container size each iteration
as defense in depth.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
