refactor(exit): pass error message to preserve_exit() (#22097)

Problem:
1. Some calls to preserve_exit() don't put a message in IObuff, so the
   IObuff printed by preserve_exit() contains unrelated information.
2. If a TUI client runs out of memory or receives a deadly signal, the
   error message is shown on alternate screen and cannot be easily seen
   because the TUI exits alternate screen soon afterwards.

Solution:
Pass error message to preserve_exit() and exit alternate screen before
printing it.

Note that this doesn't fix the problem that server error messages cannot
be easily seen on exit. This is tracked in #21608 and #21843.

1 files changed, 1 insertions, 4 deletions

diff --git a/src/nvim/tui/tui.c b/src/nvim/tui/tui.c
index f760e99262..fff5c865bf 100644
--- a/src/nvim/tui/tui.c
+++ b/src/nvim/tui/tui.c
@@ -458,9 +458,6 @@ static void tui_terminal_stop(TUIData *tui)
 
 void tui_stop(TUIData *tui)
 {
-  if (tui->stopped) {
-    return;
-  }
   tui_terminal_stop(tui);
   stream_set_blocking(tui->input.in_fd, true);   // normalize stream (#2598)
   tinput_destroy(&tui->input);
@@ -470,7 +467,7 @@ void tui_stop(TUIData *tui)
 }
 
 /// Returns true if UI `ui` is stopped.
-static bool tui_is_stopped(TUIData *tui)
+bool tui_is_stopped(TUIData *tui)
 {
   return tui->stopped;
 }