PlayMaker Version: 1.8.3.f4; Unity Version: 5.5.0f3; O.S.: Windows 10
Create a FSM Template, add a State with no Action. Close the editor and open it again. Get the following error:
System.NullReferenceException: Object reference not set to an instance of an object
at HutongGames.PlayMaker.ActionData.GetParamDataType (System.Type type) [0x00302] in c:\Users\Alex\Documents\Unity\Playmaker\Projects\Playmaker.source.unity\Assets\PlayMaker\Classes\ActionData.cs:3185
at HutongGames.PlayMaker.ActionData.TryConvertParameter (HutongGames.PlayMaker.Context context, HutongGames.PlayMaker.FsmStateAction action, System.Reflection.FieldInfo field, Int32 paramIndex) [0x006d8] in c:\Users\Alex\Documents\Unity\Playmaker\Projects\Playmaker.source.unity\Assets\PlayMaker\Classes\ActionData.cs:2451
at HutongGames.PlayMaker.ActionData.TryRecoverAction (HutongGames.PlayMaker.Context context, System.Type actionType, HutongGames.PlayMaker.FsmStateAction action, Int32 actionIndex) [0x000ef] in c:\Users\Alex\Documents\Unity\Playmaker\Projects\Playmaker.source.unity\Assets\PlayMaker\Classes\ActionData.cs:2154
at HutongGames.PlayMaker.ActionData.CreateAction (HutongGames.PlayMaker.Context context, Int32 actionIndex) [0x00206] in c:\Users\Alex\Documents\Unity\Playmaker\Projects\Playmaker.source.unity\Assets\PlayMaker\Classes\ActionData.cs:909
UnityEngine.Debug:LogError(Object)
HutongGames.PlayMakerEditor.FsmErrorChecker:DoCheckFsmForErrors(Fsm) (at c:/Users/Alex/Documents/Unity/Playmaker/Projects/Playmaker.source.unity/Assets/PlayMaker/Editor/Classes/FsmErrorChecker.cs:301)
HutongGames.PlayMakerEditor.FsmErrorChecker:DoCheckForErrors() (at c:/Users/Alex/Documents/Unity/Playmaker/Projects/Playmaker.source.unity/Assets/PlayMaker/Editor/Classes/FsmErrorChecker.cs:232)
HutongGames.PlayMakerEditor.FsmErrorChecker:Update() (at c:/Users/Alex/Documents/Unity/Playmaker/Projects/Playmaker.source.unity/Assets/PlayMaker/Editor/Classes/FsmErrorChecker.cs:197)
HutongGames.PlayMakerEditor.FsmEditor:Update() (at c:/Users/Alex/Documents/Unity/Playmaker/Projects/Playmaker.source.unity/Assets/PlayMaker/Editor/Classes/FsmEditor.cs:828)
HutongGames.PlayMakerEditor.FsmEditorWindow:Update() (at Assets/PlayMaker/Editor/FsmEditorWindow.cs:336)
UnityEditor.EditorApplication:Internal_CallUpdateFunctions()