Custom world import settings always fails with "Error Importing Settings"

When attempting to import a valid world settings json generated by "Export World Generation Settings" or custom-written, import always fails with the message:

Error Importing Settings

Can't load registry with this ops

Steps to Reproduce:

1. Generate a world with default settings.
2. Export world generation settings from that world.
3. Start creating a new world.
4. Use "More World Options" > "Import Settings" to select the newly-exported settings.

This workflow functions correctly in 1.18.2

Code analysis
apple502j: see code analysis in this comment.