Error

21:27:41 Failed to call hook 'OnDispenserGather' on plugin 'SkillTree v1.7.3' (NullReferenceException: Object reference not set to an instance of an object)
at ItemContainer.Remove (Item item) [0x00069] in <a02df9ca467442d483e493b1d5423b87>:0
at Item.SetParent (ItemContainer target) [0x00012] in <a02df9ca467442d483e493b1d5423b87>:0
at Item.RemoveFromContainer () [0x00009] in <a02df9ca467442d483e493b1d5423b87>:0
at Item.MoveToContainer (ItemContainer newcontainer, System.Int32 iTargetPos, System.Boolean allowStack, System.Boolean ignoreStackLimit, BasePlayer sourcePlayer, System.Boolean allowSwap) [0x0032b] in <a02df9ca467442d483e493b1d5423b87>:0
at Oxide.Plugins.Backpacks+ItemContainerAdapter.TryInsertItem (Item item, Oxide.Plugins.Backpacks+ItemQuery& itemQuery, System.Int32 position) [0x00025] in <a45688d0f9154e7c9e48e4fa6ecaeee6>:0
at Oxide.Plugins.Backpacks+Backpack.TryGatherItem (Item item, Oxide.Plugins.Backpacks+GatherModeStats& stats) [0x00101] in <a45688d0f9154e7c9e48e4fa6ecaeee6>:0
at Oxide.Plugins.Backpacks+InventoryWatcher.OnItemAddedRemoved (Item item, System.Boolean wasAdded) [0x00184] in <a45688d0f9154e7c9e48e4fa6ecaeee6>:0
at (wrapper delegate-invoke) System.Action`2[Item,System.Boolean].invoke_void_T1_T2(Item,bool)
at ItemContainer.Insert (Item item) [0x00047] in <a02df9ca467442d483e493b1d5423b87>:0
at Item.SetParent (ItemContainer target) [0x00039] in <a02df9ca467442d483e493b1d5423b87>:0
at Item.MoveToContainer (ItemContainer newcontainer, System.Int32 iTargetPos, System.Boolean allowStack, System.Boolean ignoreStackLimit, BasePlayer sourcePlayer, System.Boolean allowSwap) [0x00617] in <a02df9ca467442d483e493b1d5423b87>:0
at PlayerInventory.GiveItem (Item item, ItemMoveModifier modifiers, ItemContainer container, GiveItemOptions options) [0x0004a] in <a02df9ca467442d483e493b1d5423b87>:0
at PlayerInventory.GiveItem (Item item, ItemContainer container, GiveItemOptions options) [0x00000] in <a02df9ca467442d483e493b1d5423b87>:0
at BasePlayer.GiveItem (Item item, BaseEntity+GiveItemReason reason, GiveItemOptions options) [0x00059] in <a02df9ca467442d483e493b1d5423b87>:0
at Oxide.Plugins.SkillTree.HandleDispenser (ResourceDispenser dispenser, BasePlayer player, Item item, System.Boolean bonus) [0x00460] in <8d192d2d0a1d4a8ca0a0a22afb1b074e>:0
at Oxide.Plugins.SkillTree.OnDispenserGather (ResourceDispenser dispenser, BasePlayer player, Item item) [0x00000] in <8d192d2d0a1d4a8ca0a0a22afb1b074e>:0
at Oxide.Plugins.SkillTree.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x0bbde] in <8d192d2d0a1d4a8ca0a0a22afb1b074e>: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 <15f61ddda771464d8246ebdce8ff4811>:0
at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <15f61ddda771464d8246ebdce8ff4811>:0