### 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)

switch (uMsg) {
		case WM_GETMINMAXINFO: {
			
			
			
		} break;
		case WM_NCCREATE: {
			
			
			CREATESTRUCTW *pCreate = (CREATESTRUCTW *)lParam;
			WindowData *pWindowData = reinterpret_cast<WindowData *>(pCreate->lpCreateParams);
			
			pWindowData->hWnd = hWnd;
		} break;
		default: {
			
			
			
			ERR_PRINT_ONCE(vformat("Unexpected window message 0x%x received for window we cannot recognize in our collection; sequence error.", uMsg));
		} break;
	}
	if (user_proc) {
		return CallWindowProcW(user_proc, hWnd, uMsg, wParam, lParam);
	}
	return DefWindowProcW(hWnd, uMsg, wParam, lParam);
}
LRESULT DisplayServerWindows::WndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {