Function log_horizon_error 

fn log_horizon_error(error: &Error)

Records a failed horizon read, quietly when the row is simply absent.

append_to_state writes no state hash for a room’s m.room.create event, there being no state before it, so the first window of every room misses here by design. An absent row reads the same whatever left it absent, so the loud path is what remains: a fault that is not a miss at all.