NullReferenceException caused by Invoke in onVesselChange

[BrettRyland]

Hi,
I'm seeing some exceptions caused by smartparts due to the Invoke call in onVesselChange on a part that I think is getting destroyed before the invoked function is finally called.

[ERR 11:06:30.073] Exception handling event onVesselChange in class Timer:System.NullReferenceException
  at (wrapper managed-to-native) UnityEngine.MonoBehaviour.InvokeDelayed(UnityEngine.MonoBehaviour,string,single,single)
  at UnityEngine.MonoBehaviour.Invoke (System.String methodName, System.Single time) [0x00001] in <2425394cf09642369e2109953e31f62b>:0 
  at Lib.Timer.onVesselChange (Vessel newVessel) [0x0001c] in <486db0c7375c47f7909494a00dbf2916>:0 
  at EventData`1[T].Fire (T data) [0x000b0] in <4deecb19beb547f19b1ff89b4c59bd84>:0 

[EXC 11:06:30.074] NullReferenceException
        UnityEngine.MonoBehaviour.Invoke (System.String methodName, System.Single time) (at <2425394cf09642369e2109953e31f62b>:0)
        Lib.Timer.onVesselChange (Vessel newVessel) (at <486db0c7375c47f7909494a00dbf2916>:0)
        EventData`1[T].Fire (T data) (at <4deecb19beb547f19b1ff89b4c59bd84>:0)
        UnityEngine.DebugLogHandler:LogException(Exception, Object)
        ModuleManager.UnityLogHandle.InterceptLogHandler:LogException(Exception, Object)
        UnityEngine.Debug:LogException(Exception)
        EventData`1:Fire(Vessel)
        FlightGlobals:setActiveVessel(Vessel, Boolean, Boolean)
        FlightGlobals:ForceSetActiveVessel(Vessel)
        BDArmory.UI.LoadedVesselSwitcher:ForceSwitchVessel(Vessel)
        BDArmory.UI.LoadedVesselSwitcher:UpdateCamera()
        BDArmory.UI.LoadedVesselSwitcher:Update()

Incidentally, the Unity documentation recommends using coroutines instead of invoke (https://docs.unity3d.com/ScriptReference/MonoBehaviour.Invoke.html), which avoids these kinds of issues.
The pattern (in case you're unaware of it) is:

bool delayedFunctionRunning = false; // If required for exclusivity of running delayedFunction.
void onMyEvent()
{
    if (!delayedFunctionRunning)
    {
        StartCoroutine(delayedFunction(0.25f)); // Coroutines get stopped automatically if the instance is destroyed.
    }
}
IEnumerator delayedFunction(float delay)
{
    delayedFunctionRunning = true;
    yield return new WaitForSeconds(delay);
    if (part == null) yield break; // The part has been destroyed.
    // Do stuff.
    delayedFunctionRunning = false;
}