Fix linting errors

cmd/db_cleanup.go

@@ -189,6 +189,9 @@ func aptlyDbCleanup(cmd *commander.Command, args []string) error {
 			err = toDelete.ForEach(func(ref []byte) error {
 				return collectionFactory.PackageCollection().DeleteByKey(ref, batch)
 			})
+			if err != nil {
+				return fmt.Errorf("unable to delete by key: %s", err)
+			}
 
 			err = batch.Write()
 			if err != nil {

cmd/mirror_show.go

@@ -114,6 +114,9 @@ func aptlyMirrorShowJSON(cmd *commander.Command, args []string) error {
 		if repo.RefList() != nil {
 			var list *deb.PackageList
 			list, err = deb.NewPackageListFromRefList(repo.RefList(), context.NewCollectionFactory().PackageCollection(), context.Progress())
+			if err != nil {
+				return fmt.Errorf("unable to get package list: %s", err)
+			}
 
 			list.PrepareIndex()
 			list.ForEachIndexed(func(p *deb.Package) error {

cmd/snapshot_show.go

@@ -134,6 +134,9 @@ func aptlySnapshotShowJSON(cmd *commander.Command, args []string) error {
 		if snapshot.RefList() != nil {
 			var list *deb.PackageList
 			list, err = deb.NewPackageListFromRefList(snapshot.RefList(), context.NewCollectionFactory().PackageCollection(), context.Progress())
+			if err != nil {
+				return fmt.Errorf("unable to get package list: %s", err)
+			}
 
 			list.PrepareIndex()
 			list.ForEachIndexed(func(p *deb.Package) error {