internal/app/state: include et header

This is the initial step of implementing #19.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/app/state/state.go

@@ -2,14 +2,9 @@
 package state
 
 import (
-	"errors"
-
 	"hakurei.app/hst"
 )
 
-// ErrNoConfig is returned by [Cursor] when used with a nil [hst.Config].
-var ErrNoConfig = errors.New("state does not contain config")
-
 type Store interface {
 	// Do calls f exactly once and ensures store exclusivity until f returns.
 	// Returns whether f is called and any errors during the locking process.