NullReferenceException

Sorry I am getting 
NullReferenceException: Object reference not set to an instance of an object
  at Oxide.Plugins.FurnaceLevels+FurnaceUpgrades.SmeltItems () [0x001eb] in <d878904bfb9e4689b42894fe29f7c50f>:0 
  at Oxide.Plugins.FurnaceLevels+FurnaceUpgrades.Cook () [0x00014] in <d878904bfb9e4689b42894fe29f7c50f>:0 
  at InvokeHandlerBase`1[T].DoTick () [0x000be] in <259fcebfe12d4fe1a9e9cedd9876fac8>:0 
  at InvokeHandlerBase`1[T].LateUpdate () [0x0000c] in <259fcebfe12d4fe1a9e9cedd9876fac8>:0 
 
(Filename: <d878904bfb9e4689b42894fe29f7c50f> Line: 0)

Same issue here :
 

FurnaceLevels v1.4.1: Failed to call hook furnace_ui(ConsoleSystem+Arg):
System.NullReferenceException: Object reference not set to an instance of an object
at Oxide.Plugins.FurnaceLevels.GetNextPrice (System.Int32 index, System.String modType) [0x000c5] in <7dfe83efc14b4f7db651f3c82634b8a2>:0
at Oxide.Plugins.FurnaceLevels.CreateCui (BasePlayer player, System.UInt64 ovenId, System.String prefabName) [0x000bc] in <7dfe83efc14b4f7db651f3c82634b8a2>:0
at Oxide.Plugins.FurnaceLevels.furnace_ui (ConsoleSystem+Arg arg) [0x000a9] in <7dfe83efc14b4f7db651f3c82634b8a2>:0
at Oxide.Plugins.FurnaceLevels.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x009e0] in <7dfe83efc14b4f7db651f3c82634b8a2>:0
at OxidePerfCounter.main.HookPerformance (Oxide.Core.Plugins.HookMethod method, System.Object[] args, Oxide.Plugins.CSharpPlugin __instance, System.Object& __result) [0x0009c] in <b3fa7a63aa764ffb9f048e13be62c298>:0

You need to reset your config after installing new version

Sorted, thank you

Changed Status from Pending to Not a Bug