commit 424f13fe13036e75b1c80e7751b81529f4cd8e15
Author: Nicholas Marriott <nicholas.marriott@gmail.com>
Date:   Wed Apr 10 07:15:21 2024 +0000
Forwarded: not-needed

    Do not get muddled and crash if focusing a pane that is exiting,
    reported by Saul Nogueras in GitHub issue 3776.

Origin: upstream, https://github.com/tmux/tmux/commit/424f13fe13036e75b1c80e7751b81529f4cd8e15

diff --git a/window.c b/window.c
index 43c272bc8e..d53c606e07 100644
--- a/window.c
+++ b/window.c
@@ -474,7 +474,7 @@ window_pane_update_focus(struct window_pane *wp)
 	struct client	*c;
 	int		 focused = 0;
 
-	if (wp != NULL) {
+	if (wp != NULL && (~wp->flags & PANE_EXITED)) {
 		if (wp != wp->window->active)
 			focused = 0;
 		else {