### 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;
	
	
	
	scaling_3d_scale = CLAMP(p_scaling_3d_scale, 0.1, 2.0);
	RS::get_singleton()->viewport_set_scaling_3d_scale(viewport, scaling_3d_scale);
}
float Viewport::get_scaling_3d_scale() const {
	ERR_READ_THREAD_GUARD_V(0);
	return scaling_3d_scale;
}
void Viewport::set_fsr_sharpness(float p_fsr_sharpness) {
	ERR_MAIN_THREAD_GUARD;
	if (fsr_sharpness == p_fsr_sharpness) {
		return;
	}
	if (p_fsr_sharpness < 0.0f) {
		p_fsr_sharpness = 0.0f;
	}
	fsr_sharpness = p_fsr_sharpness;
	RS::get_singleton()->viewport_set_fsr_sharpness(viewport, p_fsr_sharpness);
}
float Viewport::get_fsr_sharpness() const {
	ERR_READ_THREAD_GUARD_V(0);
	return fsr_sharpness;
}
void Viewport::set_texture_mipmap_bias(float p_texture_mipmap_bias) {