[#54] Fix linter warnings

Signed-off-by: Alex Vanin <a.vanin@yadro.com>

settings.go

@@ -320,11 +320,7 @@ func mergeConfig(v *viper.Viper, fileName string) error {
 		}
 	}()
 
-	if err = v.MergeConfig(cfgFile); err != nil {
-		return err
-	}
-
-	return nil
+	return v.MergeConfig(cfgFile)
 }
 
 // newLogger constructs a zap.Logger instance for current application.