Items from non-existent NPCs are displayed

Products from NPCs that are not on the map will be displayed.
If you try to purchase one, the following error will be output to the console.

Failed to call hook 'BuyVendingItem' on plugin 'VirtualVending v1.0.1' (ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.

Parameter name: index)

at System.Collections.Generic.List`1[T].get_Item (System.Int32 index) [0x00009] in <8ce0bd04a7a04b4b9395538239d3fdd8>:0

at Oxide.Plugins.VirtualVending.BuyVendingItem (ConsoleSystem+Arg arg) [0x00224] in <bd3c59d3a4fe473e90c01a7eb9e0f149>:0

at Oxide.Plugins.VirtualVending.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00718] in <bd3c59d3a4fe473e90c01a7eb9e0f149>:0

at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <42f9bedc659b4f4786eb778d3cd58968>:0

at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000de] in <d646191a355d43a6b3ab36b7ee14c740>:0

at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <d646191a355d43a6b3ab36b7ee14c740>:0