I got this message while compiling the plugin:

Failed to call hook 'OnServerInitialized' on plugin 'StackSizeController v2.0.0' (NullReferenceException: Object reference not set to an instance of an object)

at Oxide.Plugins.StackSizeController.DetermineStack (ItemDefinition item) [0x00030] in <d71329cc728240f6861a33547d290273>:0

at Oxide.Plugins.StackSizeController.UpdateItems () [0x0003a] in <d71329cc728240f6861a33547d290273>:0

at Oxide.Plugins.StackSizeController.OnServerInitialized () [0x0000c] in <d71329cc728240f6861a33547d290273>:0

at Oxide.Plugins.StackSizeController.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x0037e] in <d71329cc728240f6861a33547d290273>:0

at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <9affce1cd15c4ec183941adef8db1722>:0
at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <4452f821def6406d834e4149849fe7ea>:0
at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <4452f821def6406d834e4149849fe7ea>:0

Can you help me pls?

Merged post

Solved with generated new config and data files. 

Failed to call hook 'OnServerInitialized' on plugin 'StackSizeController v2.0.0' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.StackSizeController.DetermineStack (ItemDefinition item) [0x00072] in <46b5151b193a4b6185733d4d65a98e1e>:0

  at Oxide.Plugins.StackSizeController.UpdateItems () [0x0003a] in <46b5151b193a4b6185733d4d65a98e1e>:0

  at Oxide.Plugins.StackSizeController.OnServerInitialized () [0x0000c] in <46b5151b193a4b6185733d4d65a98e1e>:0

  at Oxide.Plugins.StackSizeController.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x0037e] in <46b5151b193a4b6185733d4d65a98e1e>:0

  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <9affce1cd15c4ec183941adef8db1722>:0

  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <4452f821def6406d834e4149849fe7ea>:0

  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <4452f821def6406d834e4149849fe7ea>:0

Failed to call hook 'OnServerInitialized' on plugin 'StackSizeController v2.0.0' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.StackSizeController.DetermineStack (ItemDefinition item) [0x00047] in <eb2dec24c7fe40f5ac5bceca5b1fee56>:0
7 ents, 19 slprs                                                                                0b/s in, 0b/s out
  at Oxide.Plugins.StackSizeController.UpdateItems () [0x0003a] in <eb2dec24c7fe40f5ac5bceca5b1fee56>:0
  at Oxide.Plugins.StackSizeController.OnServerInitialized () [0x0000c] in <eb2dec24c7fe40f5ac5bceca5b1fee56>:0
  at Oxide.Plugins.StackSizeController.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x0037e] in <eb2dec24c7fe40f5ac5bceca5b1fee56>:0
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <9affce1cd15c4ec183941adef8db1722>:0
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <4452f821def6406d834e4149849fe7ea>:0
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <4452f821def6406d834e4149849fe7ea>:0
Loaded plugin Stack Size Controller v2.0.0 by Canopy Sheep