I used those commands and get those errors:
player.inventory.addItem(Items.ma_std_rcr_11_shard_merc, 1)
lua: error: [string "player.inventory.addItem(Ite..."]:1: attempt to index a nil value (global 'player')
Game.AddToInventory("Items.ma_std_rcr_11_shard_merc", 1)
lua: error: [string...