CBToolEditor.cs GetClassTextFile function error

[milban]

https://github.com/CloudBreadProject/CloudBread-Unity-SDK
I try this but failed and error.

error code

NullReferenceException: Object reference not set to an instance of an object
CloudBread.CBToolEditor.GetClassTextFile (System.String fileName_) (at Assets/CloudBread/Editor/CBToolEditor.cs:14)
CloudBread.CBPostman.MakeStructFromJson (System.String structName_, System.String structType_, System.String jsonText_) (at Assets/CloudBread/Editor/CBPostman.cs:318)
CloudBread.CBPostman.GenerateStruct (System.String postData_, System.String header_) (at Assets/CloudBread/Editor/CBPostman.cs:287)
CloudBread.CBPostman.DrawBodyRight () (at Assets/CloudBread/Editor/CBPostman.cs:207)
CloudBread.CBPostman.DrawBody () (at Assets/CloudBread/Editor/CBPostman.cs:70)
CloudBread.CBPostman.OnGUI () (at Assets/CloudBread/Editor/CBPostman.cs:34)
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:222)
Rethrow as TargetInvocationException: Exception has been thrown by the target of an invocation.
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:232)
System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MethodBase.cs:115)
UnityEditor.HostView.Invoke (System.String methodName, System.Object obj) (at C:/buildslave/unity/build/Editor/Mono/HostView.cs:285)
UnityEditor.HostView.Invoke (System.String methodName) (at C:/buildslave/unity/build/Editor/Mono/HostView.cs:278)
UnityEditor.HostView.InvokeOnGUI (Rect onGUIPosition) (at