Administration console - removing task before undeploying it should show an error

Steps to reproduce:
Go to cache container -> Configuration -> Deployments -> upload some task (you can use the one in attachment) -> Deploy the task -> try clicking Remove

The task is correctly not removed, since it's not undeployed yet. However, there used to be a popup windows which showed, why the task could not be removed. I think it should be put back since it's much more user-friendly.