Fix various lint issues (#1010)

1. Typo
2. Missing package doc comment
3. Tautological conditional

internal/and/and_closer.go

@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// Package and provides helpers for adding Close to io.{Reader|Writer}.
 package and
 
 import (

internal/estargz/estargz.go

@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// Package estargz adapts the containerd estargz package to our abstractions.
 package estargz
 
 import (
@@ -33,7 +34,7 @@ var _ io.ReadCloser = (*estargz.Blob)(nil)
 //  * An error if the estargz processing encountered a problem.
 //
 // Refer to estargz for the options:
-// https://pkg.go.dev/github.com/containerd/stargz-snapshotter@v0.2.0/estargz#Option
+// https://pkg.go.dev/github.com/containerd/stargz-snapshotter/estargz@v0.4.1#Option
 func ReadCloser(r io.ReadCloser, opts ...estargz.Option) (*estargz.Blob, v1.Hash, error) {
 	defer r.Close()
 

internal/gzip/zip.go

@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// Package gzip provides helper functions for interacting with gzipped streams.
 package gzip
 
 import (
@@ -72,7 +73,7 @@ func ReadCloserLevel(r io.ReadCloser, level int) io.ReadCloser {
 			return pw.CloseWithError(err)
 		}
 
-		// We dont' really care if these fail.
+		// We don't really care if these fail.
 		defer pw.Close()
 		defer r.Close()
 

internal/verify/verify.go

@@ -12,6 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// Package verify provides a ReadCloser that verifies content matches the
+// expected hash values.
 package verify
 
 import (

pkg/v1/cache/cache.go

@@ -77,7 +77,7 @@ func (l *lazyLayer) Compressed() (io.ReadCloser, error) {
 		// Layer found in the cache.
 		logs.Progress.Printf("Layer %s found (compressed) in cache", digest)
 		return cl.Compressed()
-	} else if err != nil && err != ErrNotFound {
+	} else if err != ErrNotFound {
 		return nil, err
 	}
 
@@ -99,7 +99,7 @@ func (l *lazyLayer) Uncompressed() (io.ReadCloser, error) {
 		// Layer found in the cache.
 		logs.Progress.Printf("Layer %s found (uncompressed) in cache", diffID)
 		return cl.Uncompressed()
-	} else if err != nil && err != ErrNotFound {
+	} else if err != ErrNotFound {
 		return nil, err
 	}