repository: add Checker() method to repository to replace unchecked cast

internal/repository/checker.go

@@ -51,11 +51,11 @@ func (e *PackError) Error() string {
 // Checker handles index-related operations for repository checking.
 type Checker struct {
 	packs map[restic.ID]int64
-	repo  restic.Repository
+	repo  *Repository
 }
 
 // NewChecker creates a new Checker.
-func NewChecker(repo restic.Repository) *Checker {
+func NewChecker(repo *Repository) *Checker {
 	return &Checker{
 		packs: make(map[restic.ID]int64),
 		repo:  repo,
@@ -256,7 +256,7 @@ func (c *Checker) ReadPacks(ctx context.Context, packs map[restic.ID]int64, p *p
 					}
 				}
 
-				err := CheckPack(ctx, c.repo.(*Repository), ps.id, ps.blobs, ps.size, bufRd, dec)
+				err := CheckPack(ctx, c.repo, ps.id, ps.blobs, ps.size, bufRd, dec)
 				p.Add(1)
 				if err == nil {
 					continue

internal/repository/index/master_index_test.go

@@ -347,7 +347,7 @@ var (
 	depth        = 3
 )
 
-func createFilledRepo(t testing.TB, snapshots int, version uint) (restic.Repository, restic.Unpacked[restic.FileType]) {
+func createFilledRepo(t testing.TB, snapshots int, version uint) (*repository.Repository, restic.Unpacked[restic.FileType]) {
 	repo, unpacked, _ := repository.TestRepositoryWithVersion(t, version)
 
 	for i := 0; i < snapshots; i++ {

internal/repository/repository.go

@@ -178,6 +178,10 @@ func (r *Repository) SetDryRun() {
 	r.be = dryrun.New(r.be)
 }
 
+func (r *Repository) Checker() *Checker {
+	return NewChecker(r)
+}
+
 // LoadUnpacked loads and decrypts the file with the given type and ID.
 func (r *Repository) LoadUnpacked(ctx context.Context, t restic.FileType, id restic.ID) ([]byte, error) {
 	debug.Log("load %v with id %v", t, id)

internal/repository/testing.go

@@ -164,7 +164,7 @@ func TestNewLock(_ *testing.T, repo *Repository, exclusive bool) (*restic.Lock,
 }
 
 // TestCheckRepo runs the checker on repo.
-func TestCheckRepo(t testing.TB, repo restic.Repository) {
+func TestCheckRepo(t testing.TB, repo *Repository) {
 	chkr := NewChecker(repo)
 
 	hints, errs := chkr.LoadIndex(context.TODO(), nil)