Event subscriber crash not caught by NAV

Hi all,

One of my event subscribers in NAV2016 is causing an unhandled exception.


As soon as the event is fired, I'm getting this exception in the client:


The NST event viewer:
Type: System.NullReferenceException
Message: Object reference not set to an instance of an object.
StackTrace:
at Microsoft.Dynamics.Nav.EventSubscription.NavEventScope.CallEventSubscriber(NavEventSubscription subscriber, NavCodeunit subscriberCodeunitInstance, Object[] parameters)
at Microsoft.Dynamics.Nav.EventSubscription.NavEventScope.ProcessCallToAllSubscribers(NavApplicationObjectBase callerApplicationObject, PrepareParametersCallBack prepareParameters)
at Microsoft.Dynamics.Nav.Runtime.NavRecord.ValidateField(Action`1 fieldEvent, NCLMetaField metaField, Boolean isUserInput)
at Microsoft.Dynamics.Nav.Runtime.NavRecord.Validate(NCLMetaField metaField, NavValue newValue, NavRecord callerRecord, Boolean isUserInput)
at Microsoft.Dynamics.Nav.Runtime.NavRecord.Validate(NCLMetaField metaField, NavValue newValue, NavRecord callerRecord)
at Microsoft.Dynamics.Nav.BusinessApplication.Codeunit60015.CreateServItemLines_Scope.OnRun()
at Filter.InvokeWithFilter(NavMethodScope )
at Microsoft.Dynamics.Nav.BusinessApplication.Codeunit60015.CreateServItemLines(INavRecordHandle ServRegHeader, INavRecordHandle vRecServHeader)
at Microsoft.Dynamics.Nav.BusinessApplication.Codeunit60015.WizardFinish_Scope.OnRun()
at Filter.InvokeWithFilter(NavMethodScope )
at Microsoft.Dynamics.Nav.BusinessApplication.Codeunit60015.WizardFinish(INavRecordHandle vRecServRegHeader)
at Microsoft.Dynamics.Nav.BusinessApplication.Codeunit60015.OnInvoke(Int32 memberId, Object[] args)
at Microsoft.Dynamics.Nav.BusinessApplication.Page60015.FinishWizard_Scope.OnRun()
at Filter.InvokeWithFilter(NavMethodScope )
at Microsoft.Dynamics.Nav.BusinessApplication.Page60015.FinishWizard()
at Filter.InvokeWithFilter(NavMethodScope )
at Microsoft.Dynamics.Nav.BusinessApplication.Page60015.Finish_a45_OnAction()
Source: Microsoft.Dynamics.Nav.Ncl
HResult: -2147467261

If I remove the subscriber, the issue is gone. As soon as I manually re-create it, it crashes again.
There is no code behind the validate of the field. And no real code in the subscriber (it even crashes with 'IF TRUE THEN;').

Any ideas?