fix(tui): ui may attempt reattach during shutdown #41368

Problem:
TSan CI, always at exit:

    WARNING: ThreadSanitizer: use of an invalid mutex (e.g. uninitialized or destroyed)
        #1 uv_mutex_lock
        #2 tui_flush src/nvim/tui/tui.c:1708
        #3 ui_client_event_flush
        #4 parse_msgpack src/nvim/msgpack_rpc/channel.c:259
        ...
        #10 event_teardown src/nvim/main.c:187
        #11 os_exit src/nvim/main.c:720
        ...
        #19 tinput_done_event src/nvim/tui/input.c:184

Analysis (guess):
`rpc_close_event()` may run during `event_teardown()` and reattach to
a restarted server, then `ui_client_attached=true` gets set and redraws
resume in an already-stopped TUI.

Solution:
Check `!exiting` in `rpc_close_event`, like we already do in
`channel_proc_exit_cb()`.

0 files changed, 0 insertions, 0 deletions