### Godot version

v4.0.beta17.mono.official [c40020513]

### System information

Windows 11 22H2

### Issue description

If a focused subwindow is destroyed, DisplayServerWindows may still attempt to send mouse motion events to that window, because `last_focused_window` isn't updated until another window is focused.

```
ERROR: Condition "!windows.has(p_window)" is true. Returning: Point2i()
   at: window_get_position (platform/windows/display_server_windows.cpp:999)
```

### Steps to reproduce

Run the MRP, click some non-Godot application window to focus it, then click the "CLOSE" button in the secondary window. This destroys the window without re-focusing the main window, so hovering the mouse over the main window will produce the error message above.

### Minimal reproduction project

[native_windows_hover.zip](https://github.com/godotengine/godot/files/10573386/native_windows_hover.zip)

}
		} break;
		case WT_PACKET: {
			if ((tablet_get_current_driver() == "wintab") && wintab_available && windows[window_id].wtctx) {
				PACKET packet;
				if (wintab_WTPacket(windows[window_id].wtctx, wParam, &packet)) {
					POINT coords;
					GetCursorPos(&coords);
					ScreenToClient(windows[window_id].hWnd, &coords);
					windows[window_id].last_pressure_update = 0;
					float pressure = float(packet.pkNormalPressure - windows[window_id].min_pressure) / float(windows[window_id].max_pressure - windows[window_id].min_pressure);
					double azim = (packet.pkOrientation.orAzimuth / 10.0f) * (Math_PI / 180);
					double alt = Math::tan((Math::abs(packet.pkOrientation.orAltitude / 10.0f)) * (Math_PI / 180));
					bool inverted = packet.pkStatus & TPS_INVERT;
					Vector2 tilt = (windows[window_id].tilt_supported) ? Vector2(Math::atan(Math::sin(azim) / alt), Math::atan(Math::cos(azim) / alt)) : Vector2();
					
					if (!old_invalid && coords.x == old_x && coords.y == old_y && windows[window_id].last_pressure == pressure && windows[window_id].last_tilt == tilt && windows[window_id].last_pen_inverted == inverted) {
						break;
					}
					windows[window_id].last_pressure = pressure;
					windows[window_id].last_tilt = tilt;
					windows[window_id].last_pen_inverted = inverted;
					
					if (!windows[window_id].window_has_focus && mouse_mode == MOUSE_MODE_CAPTURED) {
						break;
					}
					Ref<InputEventMouseMotion> mm;
					mm.instantiate();
					mm->set_window_id(window_id);
					mm->set_ctrl_pressed(GetKeyState(VK_CONTROL) < 0);