Always defer *sql.Rows.Close and consult with Err (#844)

* Always defer *sql.Rows.Close and consult with Err

database/sql.Rows.Next() makes sure to call Close only after exhausting
result rows which would NOT happen when returning early from a bad Scan.
Close being idempotent makes it a great candidate to get always deferred
regardless of what happens later on the result set.

This change also makes sure call Err() after exhausting Next() and
propagate non-nil results from it as the documentation advises.

Closes #764

Signed-off-by: Kiril Vladimiroff <kiril@vladimiroff.org>

* Override named result parameters in last returns

Signed-off-by: Kiril Vladimiroff <kiril@vladimiroff.org>

* Do the same over new changes that got merged

Signed-off-by: Kiril Vladimiroff <kiril@vladimiroff.org>

Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>

mediaapi/storage/postgres/thumbnail_table.go

@@ -144,6 +144,7 @@ func (s *thumbnailStatements) selectThumbnails(
 	if err != nil {
 		return nil, err
 	}
+	defer rows.Close() // nolint: errcheck
 
 	var thumbnails []*types.ThumbnailMetadata
 	for rows.Next() {
@@ -167,5 +168,5 @@ func (s *thumbnailStatements) selectThumbnails(
 		thumbnails = append(thumbnails, &thumbnailMetadata)
 	}
 
-	return thumbnails, err
+	return thumbnails, rows.Err()
 }