When a content pack edits a dialogue file, broken dialogue entries can crash the game. Validate patches before or after they're applied to detect broken dialogue entries; if an entry is broken, show a warning and revert the change.

This is a bit tricky to do, since dialogue can refer to other dialogue (which might have been added by another mod). It's somewhat addressed via SMAPI 2.8 which will intercept dialogue parse errors, log them, and substitute a default dialogue string.