Fix score serialisation failing for unknown mod properties
Fix score serialisation failing for unknown mod properties

johnneijzen/osu,ppy/osu,EVAST9919/osu,NeoAdonis/osu,peppy/osu,NeoAdonis/osu,peppy/osu,smoogipoo/osu,johnneijzen/osu,EVAST9919/osu,NeoAdonis/osu,peppy/osu,2yangk23/osu,smoogipoo/osu,ppy/osu,UselessToucan/osu,2yangk23/osu,ppy/osu,peppy/osu-new,UselessToucan/osu,UselessToucan/osu,smoogipooo/osu,smoogipoo/osu