X_EXERCISE_ACTOR_USER_UNSEATED
Means
the exercise pass could not seat its actor's x_users row
Typical cause
x exercise writes one x_users row per actor it acts as (an app on @ultimat3/auth reads ctx.actor.id as one), and the insert was refused — a column the app added to x_users with no default, usually
Fix
x exercise --json # after a migration under packages/db/migrations/ gives the column the app added to x_users a default, or makes it nullable