### 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)

SUB_WINDOW_DRAG_DISABLED,
		SUB_WINDOW_DRAG_MOVE,
		SUB_WINDOW_DRAG_CLOSE,
		SUB_WINDOW_DRAG_RESIZE,
	};
	enum SubWindowResize {
		SUB_WINDOW_RESIZE_DISABLED,
		SUB_WINDOW_RESIZE_TOP_LEFT,
		SUB_WINDOW_RESIZE_TOP,
		SUB_WINDOW_RESIZE_TOP_RIGHT,
		SUB_WINDOW_RESIZE_LEFT,
		SUB_WINDOW_RESIZE_RIGHT,
		SUB_WINDOW_RESIZE_BOTTOM_LEFT,
		SUB_WINDOW_RESIZE_BOTTOM,
		SUB_WINDOW_RESIZE_BOTTOM_RIGHT,
		SUB_WINDOW_RESIZE_MAX
	};
	struct SubWindow {
		Window *window = nullptr;
		RID canvas_item;
	};
	
	VRSMode vrs_mode = VRS_DISABLED;
	Ref<Texture2D> vrs_texture;
	struct GUI {
		
		bool forced_mouse_focus = false; 
		bool mouse_in_viewport = true;
		bool key_event_accepted = false;