Fix lint errors (#1390)

* use increment and decrement operators.

* remove unnecessary else branches.

* fix package comment with leading space.

* fix receiver names.

* fix error strings.

* remove omittable code.

* remove redundant return statement.

* Revert changes (code is generated.)

* use cfg as receiver name for all config-related types.

* use lsi as the receiver name for the LastSignedInfo type.

scripts/wal2json/main.go

@@ -4,6 +4,7 @@
 	Usage:
 			wal2json <path-to-wal>
 */
+
 package main
 
 import (