SDL: Fixed crash if a window couldn't be created on Windows

SDL Commits
1 
From 3415bc920ab54cc41708a0eafce30b915faf67e1 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Wed, 19 Mar 2025 20:09:47 -0700
Subject: [PATCH] Fixed crash if a window couldn't be created on Windows

Fixes https://github.com/libsdl-org/SDL/issues/11482
---
 src/video/windows/SDL_windowswindow.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/video/windows/SDL_windowswindow.c b/src/video/windows/SDL_windowswindow.c
index 76d93f2852272..e9f911d123d98 100644
--- a/src/video/windows/SDL_windowswindow.c
+++ b/src/video/windows/SDL_windowswindow.c
@@ -1311,7 +1311,7 @@ SDL_FullscreenResult WIN_SetWindowFullscreen(SDL_VideoDevice *_this, SDL_Window
 #if !defined(SDL_PLATFORM_XBOXONE) && !defined(SDL_PLATFORM_XBOXSERIES)
     SDL_DisplayData *displaydata = display->internal;
     SDL_WindowData *data = window->internal;
-    HWND hwnd = data->hwnd;
+    HWND hwnd = data ? data->hwnd : NULL;
     MONITORINFO minfo;
     DWORD style, styleEx;
     HWND top;