job scheduler rules undefined index

Seems to work on the latest version.
IMO something we should get in as not everyone is using the default interval settings.

Rebased to make sure the latest version is still working.

You are not meant to be using the simple scheduler with custom cron rules, only predefined presets are supported. For custom rules, use the crontab scheduler.

You won't be able to edit this and will lose your settings if you ever edit and save this. There should possibly be some kind of validation for this, this doesn't seem like a complete fix.

Fair point. I got this error while using some config that had this applied on the simple scheduler.

Conclusion: The feature in the initial issue is already in place if you use the crontab scheduler.

Config validation should be able to catch the unsupported simple options.
If the validation is in place, the above fix should not be necessary anymore.