Inappropriate message / incorrect handling, when an old config references datasets/vols that no longer exist.

This could be a generic problem, hence the vague title. Please retitle better.

Situation:

I went to set up an automated snapshot. My config for some reason included a past automated snap for a ZVOL, but the ZVOL no longer existed. The attached screenshot is what I got.

UI issues:

1. The UI states "Datasets" which is misdeading.  Suggests ZVOLs can't be a subject of an automated snap. Of course, they can be.
2. If for whatever reason a target doesn't exist, there are many good ways to handle it (error message "Target does not exist", or silently delete from config being 2 of them). "Invalid dataset" when the target isn't even a dataset, and no hint what is "invalid" about it, is a very poor error message.