well we would want to do something like having a config value for 'allowed actions'. What Eddie suggested could be weird since then you would have to have a worker registered for a specific action type before you can create schedules of those actions.

Giving the user this kind of warning is definitely a feature and not a bug. We can talk about it later and it should remain separate from this. I also want to make sure we don't get in the habit of trying to provide every feature, safety net, or failsafe we can think of as that would probably create some giant ball of cruft that nobody can figure out how to use. But it is definitely awesome to be thinking about these things so thanks for bringing it up :)