The original bug has been fixed by modernizing infrastructure, but this modernization isn't yet complete.
---
// Original Description //
Steps to repro:
# Using the Config UI, create a JSON config for `maniphest.priorities`
# Save the config
# Using the UI, blow away that JSON string and save the form with an empty config
# Observe that the config is now set to `null`, which breaks lots of pages:
{F5002123}