NullReferenceException at DetermineStack

I am getting this error and the plugin isnt working.

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 <c33a4ad46a9f4ac9bda57b9ab4d86674>:0
at Oxide.Plugins.StackSizeController.UpdateItems () [0x0003a] in <c33a4ad46a9f4ac9bda57b9ab4d86674>:0
at Oxide.Plugins.StackSizeController.OnServerInitialized () [0x0000c] in <c33a4ad46a9f4ac9bda57b9ab4d86674>:0
at Oxide.Plugins.StackSizeController.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x0037e] in <c33a4ad46a9f4ac9bda57b9ab4d86674>: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
Same here 
| 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 <72d7d2b663e748e5a54f62e9ab754f03>:0

at Oxide.Plugins.StackSizeController.UpdateItems () [0x0003a] in <72d7d2b663e748e5a54f62e9ab754f03>:0

at Oxide.Plugins.StackSizeController.OnServerInitialized () [0x0000c] in <72d7d2b663e748e5a54f62e9ab754f03>:0

at Oxide.Plugins.StackSizeController.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x0037e] in <72d7d2b663e748e5a54f62e9ab754f03>: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