### 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_MAIN_THREAD_GUARD;
	if (gui.subwindow_focused) {
		gui.subwindow_focused->push_text_input(p_text);
		return;
	}
	if (gui.key_focus) {
		gui.key_focus->call("set_text", p_text);
	}
}
Viewport::SubWindowResize Viewport::_sub_window_get_resize_margin(Window *p_subwindow, const Point2 &p_point) {
	if (p_subwindow->get_flag(Window::FLAG_BORDERLESS) || p_subwindow->get_flag(Window::FLAG_RESIZE_DISABLED)) {
		return SUB_WINDOW_RESIZE_DISABLED;
	}
	Rect2i r = Rect2i(p_subwindow->get_position(), p_subwindow->get_size());
	int title_height = p_subwindow->get_theme_constant(SNAME("title_height"));
	r.position.y -= title_height;
	r.size.y += title_height;
	if (r.has_point(p_point)) {
		return SUB_WINDOW_RESIZE_DISABLED; 
	}
	int dist_x = p_point.x < r.position.x ? (p_point.x - r.position.x) : (p_point.x > (r.position.x + r.size.x) ? (p_point.x - (r.position.x + r.size.x)) : 0);
	int dist_y = p_point.y < r.position.y ? (p_point.y - r.position.y) : (p_point.y > (r.position.y + r.size.y) ? (p_point.y - (r.position.y + r.size.y)) : 0);
	int limit = p_subwindow->get_theme_constant(SNAME("resize_margin"));
	if (ABS(dist_x) > limit) {
		return SUB_WINDOW_RESIZE_DISABLED;
	}