### Godot version

4.1.dev 2e273f0e35800f2bcc7c05db54100caa97928f69

### System information

macOS 13.4

### Issue description

Removing a SpinBox from the node tree using `remove_child` during the line edit text submit signal will crash the engine.

```
handle_crash: Program crashed with signal 11
Engine version: Godot Engine v4.1.dev.custom_build (2e273f0e35800f2bcc7c05db54100caa97928f69)
Dumping the backtrace. Please include this when reporting the bug to the project developer.
[1] 1   libsystem_platform.dylib            0x0000000183b5aa24 _sigtramp + 56
[2] Viewport::gui_get_focus_owner() (in godot.macos.editor.arm64) + 32
[3] SpinBox::_line_edit_focus_exit() (in godot.macos.editor.arm64) + 28
[4] CallQueue::_call_function(Callable const&, Variant const*, int, bool) (in godot.macos.editor.arm64) + 336
[5] CallQueue::flush() (in godot.macos.editor.arm64) + 908
[6] SceneTree::physics_process(double) (in godot.macos.editor.arm64) + 244
[7] Main::iteration() (in godot.macos.editor.arm64) + 528
```

### Steps to reproduce

Open the minimal reproduction project, click on the SpinBox, press enter, and the engine crashes.

### Minimal reproduction project

[SpinBoxTextSubmitCrash.zip](https://github.com/godotengine/godot/files/11631081/SpinBoxTextSubmitCrash.zip)

ERR_READ_THREAD_GUARD_V(MSAA_DISABLED);
	return msaa_2d;
}
void Viewport::set_msaa_3d(MSAA p_msaa) {
	ERR_MAIN_THREAD_GUARD;
	ERR_FAIL_INDEX(p_msaa, MSAA_MAX);
	if (msaa_3d == p_msaa) {
		return;
	}
	msaa_3d = p_msaa;
	RS::get_singleton()->viewport_set_msaa_3d(viewport, RS::ViewportMSAA(p_msaa));
}
Viewport::MSAA Viewport::get_msaa_3d() const {
	ERR_READ_THREAD_GUARD_V(MSAA_DISABLED);
	return msaa_3d;
}
void Viewport::set_screen_space_aa(ScreenSpaceAA p_screen_space_aa) {
	ERR_MAIN_THREAD_GUARD;
	ERR_FAIL_INDEX(p_screen_space_aa, SCREEN_SPACE_AA_MAX);
	if (screen_space_aa == p_screen_space_aa) {
		return;
	}
	screen_space_aa = p_screen_space_aa;
	RS::get_singleton()->viewport_set_screen_space_aa(viewport, RS::ViewportScreenSpaceAA(p_screen_space_aa));
}
Viewport::ScreenSpaceAA Viewport::get_screen_space_aa() const {
	ERR_READ_THREAD_GUARD_V(SCREEN_SPACE_AA_DISABLED);
	return screen_space_aa;
}
void Viewport::set_use_taa(bool p_use_taa) {