Remove obsolete cleanup helpers

internal/storage/fake/backend.go

@@ -3,7 +3,6 @@ package fake
 import (
 	"bytes"
 	"context"
-	"errors"
 	"io"
 	"sort"
 	"strings"
@@ -133,14 +132,14 @@ func (b *Backend) Walk(ctx context.Context, prefix string, opts storage.WalkOpti
 	if err := storage.ValidatePrefix(prefix); err != nil {
 		return err
 	}
+	emitter := storage.NewWalkEmitter(ctx, backendName, opts, fn)
 	if entry, err := b.Stat(ctx, prefix); err == nil && entry.Type != storage.EntryTypeDirectory {
-		return emit(ctx, entry, opts, fn)
+		return storage.FinishWalk(emitter.Emit(entry))
 	} else if err != nil && !storage.IsNotFound(err) {
 		return err
 	}
 
 	entries := b.entries()
-	visited := 0
 	for _, entry := range entries {
 		if entry.Path == "" || !entryBelow(prefix, entry.Path) {
 			continue
@@ -148,33 +147,15 @@ func (b *Backend) Walk(ctx context.Context, prefix string, opts storage.WalkOpti
 		if !opts.Recursive && !isImmediateChild(prefix, entry.Path) {
 			continue
 		}
-		if opts.Limit > 0 && visited >= opts.Limit {
-			return nil
-		}
-		visited++
-		if err := ctx.Err(); err != nil {
-			return err
-		}
-		if err := fn(entry); err != nil {
-			if errors.Is(err, storage.ErrStopWalk) {
-				return nil
-			}
-			return storage.NewError(storage.OpWalk, backendName, entry.Path, storage.ErrUnknown, err)
+		if err := emitter.Emit(entry); err != nil {
+			return storage.FinishWalk(err)
 		}
 	}
 	return nil
 }
 
 func (b *Backend) HasAny(ctx context.Context, prefix string) (bool, error) {
-	found := false
-	err := b.Walk(ctx, prefix, storage.WalkOptions{Recursive: false, Limit: 1}, func(storage.Entry) error {
-		found = true
-		return storage.ErrStopWalk
-	})
-	if err != nil {
-		return false, err
-	}
-	return found, nil
+	return storage.HasAny(ctx, b, prefix)
 }
 
 func (b *Backend) DeleteManagedBundle(ctx context.Context, bundlePath string, managedOutputPaths []string, opts storage.DeleteOptions) error {
@@ -302,19 +283,6 @@ func (b *Backend) entries() []storage.Entry {
 	return entries
 }
 
-func emit(ctx context.Context, entry storage.Entry, opts storage.WalkOptions, fn storage.WalkFunc) error {
-	if opts.Limit > 0 && opts.Limit < 1 {
-		return nil
-	}
-	if err := ctx.Err(); err != nil {
-		return err
-	}
-	if err := fn(entry); err != nil && !errors.Is(err, storage.ErrStopWalk) {
-		return err
-	}
-	return nil
-}
-
 func entryBelow(prefix, path string) bool {
 	if prefix == "" {
 		return path != ""