edit: forgot to mention, bringing out an SRB also throws an exception:  

[ERR 21:26:00.733] Exception handling event onEditorShipModified in class SSTUEngineStatDisplay:System.NullReferenceException: Object reference not set to an instance of an object
  at SSTUTools.SSTUEngineStatDisplay.getEnginePropellantMass (.ModuleEngines engine) [0x00000] in <filename unknown>:0 
  at SSTUTools.SSTUEngineStatDisplay.updateStats () [0x00000] in <filename unknown>:0 
  at SSTUTools.SSTUEngineStatDisplay.editorVesselModified (.ShipConstruct ship) [0x00000] in <filename unknown>:0 
  at EventData`1[ShipConstruct].Fire (.ShipConstruct data) [0x00000] in <filename unknown>:0 

[EXC 21:26:00.734] NullReferenceException: Object reference not set to an instance of an object
    SSTUTools.SSTUEngineStatDisplay.getEnginePropellantMass (.ModuleEngines engine)
    SSTUTools.SSTUEngineStatDisplay.updateStats ()
    SSTUTools.SSTUEngineStatDisplay.editorVesselModified (.ShipConstruct ship)
    EventData`1[ShipConstruct].Fire (.ShipConstruct data)
    UnityEngine.Debug:LogException(Exception)
    EventData`1:Fire(ShipConstruct)
    ThrottleControlledAvionics.TCAEngineInfo:update_status()
    ThrottleControlledAvionics.TCAEngineInfo:OnStart(StartState)
    Part:ModulesOnStart()
    <Start>c__Iterator0:MoveNext()
    UnityEngine.SetupCoroutine:InvokeMoveNext(IEnumerator, IntPtr)