### Godot version

Godot Engine v4.0.stable.official.92bee43ad

### System information

Windows 10

### Issue description

The documentation states that passing ```null``` into the image parameter of ```set_custom_mouse_cursor``` will change it back to the system cursor, however I find that it removes the cursor's image entirely, rather than setting it to the system's cursor.


### Steps to reproduce

```var isimage = false
var theimage = load("res://final.png")

func _on_my_button_pressed():
    if isimage == false:
        Input.set_custom_mouse_cursor(theimage, Input.CURSOR_ARROW, Vector2(16,16))
        isimage = true
        
    else:
        Input.set_custom_mouse_cursor(null)
        isimage = false```

When the button is pressed, the cursor is meant to change to the new cursor. When it has been pressed a second time, it changes back to the default cursor. However, upon pressing it a second time, it simply disappears. The cursor becomes visible again when the cursor exits and re-enters the window.

### Minimal reproduction project

[null mouse.zip](https://github.com/godotengine/godot/files/10901969/null.mouse.zip)

ERR_FAIL_INDEX_V(p_screen, get_screen_count(), Ref<Image>());
	switch (p_screen) {
		case SCREEN_PRIMARY: {
			p_screen = get_primary_screen();
		} break;
		case SCREEN_OF_MAIN_WINDOW: {
			p_screen = window_get_current_screen(MAIN_WINDOW_ID);
		} break;
		default:
			break;
	}
	Point2i pos = screen_get_position(p_screen) + _get_screens_origin();
	Size2i size = screen_get_size(p_screen);
	POINT p1;
	p1.x = pos.x;
	p1.y = pos.y;
	POINT p2;
	p2.x = pos.x + size.x;
	p2.y = pos.y + size.y;
	if (win81p_LogicalToPhysicalPointForPerMonitorDPI) {
		win81p_LogicalToPhysicalPointForPerMonitorDPI(0, &p1);
		win81p_LogicalToPhysicalPointForPerMonitorDPI(0, &p2);
	}
	Ref<Image> img;
	HDC dc = GetDC(0);
	if (dc) {
		HDC hdc = CreateCompatibleDC(dc);
		int width = p2.x - p1.x;