show throw exception in UI from CustomProvider

Hi

I use gantt chart viewer in my company project.

it's realy perfect but i have some problem with custom provider

i want show a message in UI when something is wrong is customProvider
for example use delete a dependency but in deleteDependency function ,we understand use haven't dependency delete permittion and we throw a exception.

but in UI, dependency line is deleted.

we want show dependency line in UI if delete function return throw exception and show a message to user contain throw message.