X_DB_SCHEMA_UNDECLARED
Means
a migration records schema no entity declares
Typical cause
the other direction, and a different repair: the database carries a constraint, column or index the entities no longer ask for. Reported separately from X_DB_SCHEMA_UNMIGRATED because "your database is missing this" and "your last generation lost something" are not one finding
Fix
delete the stale declaration, or bun run x -- db gen "drop what the entities no longer declare" if the removal is intended