Added some simple argument validation for functions just to prevent some useless calls to the BGG API; functions return None instead of raising an Exception when some object is not found (e.g. user)
Added some simple argument validation for functions just to prevent some useless calls to the BGG API; functions return None instead of raising an Exception when some object is not found (e.g. user)

PigheadedGnu/boardgamegeek,lcosmin/boardgamegeek