Buy Item NullReferenceException

[Krilliac]

System.NullReferenceException
HResult=0x80004003
Message=Object reference not set to an instance of an object.
Source=WorldServer
StackTrace:
at Mangos.World.Objects.WS_NPCs.On_CMSG_BUY_ITEM(PacketClass& packet, ClientClass& client) in D:\USB DRIVE\Work\MangosSharp\MangosSharp\Source\Services\Mangos.World\Objects\WS_NPCs.cs:line 815

[Krilliac]

Occurs after using nullchar command, then trying to buy an item