Enforce default values for Configs

[lomky]

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• What are we trying to do?
  Config value typos can lead to problems of all sizes. Let's make it required they have a default value or throw a fit.

• What feature or behavior is this required for?
  App stablity

• How could we solve this issue? (Not knowing is okay!)
  Application error in the Config model if we haven't coded a valid DEFAULT.

• Anything else?
  Very important typo #3394 Bugfix: Standardize shared_reset_days key #3393