add_mooh make error

Compiling src/devices/bus/spi/spi65.cpp...
In file included from ../../../../../src/devices/bus/spi/spi65.cpp:1:
In file included from ../../../../../src/emu/emu.h:109:
/Volumes/Projects/Projects/git/tlindner/mame/build/projects/sdl/mame/gmake-osx-clang/../../../../../src/emu/device.ipp:45:16: error: no viable overloaded '='
        return finder = result;
               ~~~~~~ ^ ~~~~~~
../../../../../src/devices/bus/spi/spi65.cpp:101:12: note: in instantiation of function template specialization 'emu::detail::device_type_impl<spi65_slot_device>::operator()<device_spi65_interface, true, unsigned int, void (&)(device_slot_interface &), char
      const (&)[7]>' requested here
        SPI65_SLOT(config, m_slots[0], DERIVED_CLOCK(1, 1), spi65_bus, "sdcard");
                  ^
In file included from ../../../../../src/devices/bus/spi/spi65.cpp:1:
In file included from ../../../../../src/emu/emu.h:65:
/Volumes/Projects/Projects/git/tlindner/mame/build/projects/sdl/mame/gmake-osx-clang/../../../../../src/emu/devfind.h:538:7: note: candidate function (the implicit copy assignment operator) not viable: no known conversion from 'spi65_slot_device' to
      'const device_finder<device_spi65_interface, true>' for 1st argument
class device_finder : public object_finder_base<DeviceClass, Required>
      ^
/Volumes/Projects/Projects/git/tlindner/mame/build/projects/sdl/mame/gmake-osx-clang/../../../../../src/emu/devfind.h:570:72: note: candidate template ignored: requirement 'std::is_convertible<spi65_slot_device *, device_spi65_interface *>::value' was not
      satisfied [with T = spi65_slot_device]
        std::enable_if_t<std::is_convertible<T *, DeviceClass *>::value, T &> operator=(T &device)