From f0b2f6c3cd1317310a75772d28c02f2a65f42a21 Mon Sep 17 00:00:00 2001
From: Hilderin <81109165+Hilderin@users.noreply.github.com>
Date: Thu, 6 Feb 2025 17:05:06 -0500
Subject: [PATCH] Fix error when embedded window is closed while resizing

(cherry picked from commit b61499353f23ff41d6e8958dc2324388e607df40)
---
 scene/main/viewport.cpp | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/scene/main/viewport.cpp b/scene/main/viewport.cpp
index f7fd1a2c5a7..0098f4dc92a 100644
--- a/scene/main/viewport.cpp
+++ b/scene/main/viewport.cpp
@@ -317,7 +317,13 @@ void Viewport::_sub_window_register(Window *p_window) {
 
 void Viewport::_sub_window_update(Window *p_window) {
 	int index = _sub_window_find(p_window);
-	ERR_FAIL_COND(index == -1);
+
+	// _sub_window_update is sometimes called deferred, and the window may have been closed since then.
+	// For example, when the user resizes the game window.
+	// In that case, _sub_window_find will not find it, which is expected.
+	if (index == -1) {
+		return;
+	}
 
 	SubWindow &sw = gui.sub_windows.write[index];
 	sw.pending_window_update = false;