Remove unused variables/types/functions

[staticcheck](https://staticcheck.io/) reported a number of unused
fields, functions, types, and variables across the code.

Where possible, use them (assert unchecked errors in tests, for example)
and otherwise remove them.

1 files changed, 0 insertions, 15 deletions

diff --git a/plumbing/format/packfile/fsobject.go b/plumbing/format/packfile/fsobject.go
index a395d17..238339d 100644
--- a/plumbing/format/packfile/fsobject.go
+++ b/plumbing/format/packfile/fsobject.go
@@ -13,7 +13,6 @@ import (
 // FSObject is an object from the packfile on the filesystem.
 type FSObject struct {
 	hash                 plumbing.Hash
-	h                    *ObjectHeader
 	offset               int64
 	size                 int64
 	typ                  plumbing.ObjectType
@@ -118,17 +117,3 @@ func (o *FSObject) Type() plumbing.ObjectType {
 func (o *FSObject) Writer() (io.WriteCloser, error) {
 	return nil, nil
 }
-
-type objectReader struct {
-	io.ReadCloser
-	f billy.File
-}
-
-func (r *objectReader) Close() error {
-	if err := r.ReadCloser.Close(); err != nil {
-		_ = r.f.Close()
-		return err
-	}
-
-	return r.f.Close()
-}