VOL-3344 - Enabled default linters and fixed found issues.

Also disabled govet's variable shadowing check, since this is very useful for isolating multiple "err"ors in a row.

Change-Id: Icd70c723c406c5986b8cfe4535ad7daa0752e48c
diff --git a/cmd/openolt-adapter/main.go b/cmd/openolt-adapter/main.go
index b92d989..29b715f 100644
--- a/cmd/openolt-adapter/main.go
+++ b/cmd/openolt-adapter/main.go
@@ -486,7 +486,12 @@
 
 	realMain()
 
-	defer log.CleanUp()
+	defer func() {
+		err := log.CleanUp()
+		if err != nil {
+			logger.Errorw(context.Background(), "unable-to-flush-any-buffered-log-entries", log.Fields{"error": err})
+		}
+	}()
 
 	// Print version / build information and exit
 	if cf.DisplayVersionOnly {