Attribute reader shutdown failures to checks that read content

internal/validation/tree.go

@@ -19,6 +19,7 @@ type CandidateTree struct {
 	byPath         map[string]int
 	directories    map[string]struct{}
 	blobReader     *git.BlobReader
+	blobReads      uint64
 	symlinkTargets map[string]string
 	closed         bool
 	closeErr       error
@@ -113,6 +114,7 @@ func (tree *CandidateTree) readBlob(ctx context.Context, entry git.TreeEntry) ([
 		}
 		tree.blobReader = git.NewBlobReader(operationContext, tree.repositoryDir)
 	}
+	tree.blobReads++
 	contents, err := tree.blobReader.Read(ctx, entry.ObjectID)
 	if err != nil {
 		return nil, fmt.Errorf("read committed path %q: %w", entry.Path, err)