Return an empty array when the sender is from system.
Return an empty array when the sender is from system.

smoogipoo/osu,peppy/osu-new,peppy/osu,smoogipoo/osu,UselessToucan/osu,UselessToucan/osu,smoogipoo/osu,ppy/osu,ppy/osu,NeoAdonis/osu,UselessToucan/osu,NeoAdonis/osu,smoogipooo/osu,peppy/osu,peppy/osu,NeoAdonis/osu,ppy/osu