Misconfigured packs may not provide an error while being generated

[smonn]

Overview

A pack that was not configured correctly will end up show as "0 of 0 remaining".

To reproduce

Steps to reproduce the behavior:

1. Create a new pack template
2. Don't assign any NFT templates and then publish the pack template
3. Monitor the Scribe logs

Expected behavior

A helpful error should be logged and ideally an admin should be notified.

Additional context

Additionally, can we add a validation check for packs to require at least one NFT template again? And also prevent assigning NFT templates to more than one pack template? Maybe also make the UI ignore misconfigured packs?