Can't access one of my NPC Shops anymore

Hello there!

Since recently - likely wipe day - players are unable to access one of my 4 NPC Shops I have placed in the world. If a player (or myself) tries to access that NPC Shop the vending interface opens for a fraction of a second, only to close straight again. The other 3 NPCs do work fine. Here is the error message that is emitted to the Server console:

Failed to call internal hook 'CanLootEntity' on plugin 'NPCShop v2.11.1' [1627232611] (Object reference not set to an instance of an object)
   at void Oxide.Plugins.NPCShop.ShowUILots(BasePlayer player, ulong ID, bool isAdmin, bool preview) in /home/container/carbon/plugins/NPCShop.cs:line 1562
   at void Oxide.Plugins.NPCShop.ShowUIMain(BasePlayer player, ulong ID, bool isAdmin) in /home/container/carbon/plugins/NPCShop.cs:line 1689
   at object Oxide.Plugins.NPCShop.CanLootEntity(BasePlayer player, ResourceExtractorFuelStorage entity) in /home/container/carbon/plugins/NPCShop.cs:line 147
   at object Oxide.Plugins.NPCShop.InternalCallHook(uint hook, object[] args) in NPCShop.cs/Internal:line 61

Find my "NPCShop.json" config in the attached .txt file. The problematic NPC is "Axel the Axe". Thanks in advance for looking.

NPCShop.txt