### Godot version

v4.1.1.stable.official [bd6af8e0e]

### System information

Godot v4.1.1.stable - Debian GNU/Linux 12 (bookworm) 12 - Vulkan (Forward+) - integrated Intel(R) HD Graphics 5500 (BDW GT2) () - Intel(R) Core(TM) i5-5300U CPU @ 2.30GHz (4 Threads)

### Issue description

Attempting to open a child window from a window while having the `focus_exited` signal connected to the `hide` method, crashes Godot with signal 4 (SIGILL)
I have a backtrace, though it may not really be useful, since I didn't want to make my own build of godot with debug symbols. I hope however that the MRE makes up for the lack of a proper backtrace on my side.
```
================================================================
handle_crash: Program crashed with signal 4
Engine version: Godot Engine v4.1.1.stable.official (bd6af8e0ea69167dd0627f3bd54f9105bda0f8b5)
Dumping the backtrace. Please include this when reporting the bug to the project developer.
[1] /lib/x86_64-linux-gnu/libc.so.6(+0x3bf90) [0x7f586db17f90] (??:0)
[2] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0x2d5f7b6] (??:0)
[3] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0x2d5fa78] (??:0)
[4] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0x2dfcdf7] (??:0)
[5] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0x2dfd587] (??:0)
[6] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0x2dfe1b9] (??:0)
[7] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0x2d98f17] (??:0)
[8] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0x47d7128] (??:0)
[9] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0x461cac4] (??:0)
[10] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0x483b9d1] (??:0)
[11] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0x2ded3de] (??:0)
[12] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0x2dede9d] (??:0)
[13] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0x2d365f0] (??:0)
[14] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0x2d7c325] (??:0)
[15] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0x2d7f9ec] (??:0)
[16] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0x2d802e4] (??:0)
[17] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0x2da6ca5] (??:0)
[18] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0xeb6b10] (??:0)
[19] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0x45be723] (??:0)
[20] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0x45bf97e] (??:0)
[21] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0xeb71bf] (??:0)
[22] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0xe46433] (??:0)
[23] /lib/x86_64-linux-gnu/libc.so.6(+0x2718a) [0x7f586db0318a] (??:0)
[24] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x85) [0x7f586db03245] (??:0)
[25] /home/monix/.local/share/hourglass/versions/4.1.1/godot() [0xe777ae] (??:0)
-- END OF BACKTRACE --
================================================================
```
What I expect to happen instead:
Either the engine failing with a proper error, or hiding the window, or keeping both windows visible.

### Steps to reproduce

Download, and run the MRE
Press the Browse button in the window that appears
Crash occurs

### Minimal reproduction project

[sigill-mre.zip](https://github.com/godotengine/godot/files/12383126/sigill-mre.zip)

ERR_MAIN_THREAD_GUARD;
	if (use_taa == p_use_taa) {
		return;
	}
	use_taa = p_use_taa;
	RS::get_singleton()->viewport_set_use_taa(viewport, p_use_taa);
}
bool Viewport::is_using_taa() const {
	ERR_READ_THREAD_GUARD_V(false);
	return use_taa;
}
void Viewport::set_use_debanding(bool p_use_debanding) {
	ERR_MAIN_THREAD_GUARD;
	if (use_debanding == p_use_debanding) {
		return;
	}
	use_debanding = p_use_debanding;
	RS::get_singleton()->viewport_set_use_debanding(viewport, p_use_debanding);
}
bool Viewport::is_using_debanding() const {
	ERR_READ_THREAD_GUARD_V(false);
	return use_debanding;
}
void Viewport::set_mesh_lod_threshold(float p_pixels) {
	ERR_MAIN_THREAD_GUARD;
	mesh_lod_threshold = p_pixels;
	RS::get_singleton()->viewport_set_mesh_lod_threshold(viewport, mesh_lod_threshold);
}
float Viewport::get_mesh_lod_threshold() const {