Clean up lint in various packages

Changes fall into one of the following:

- gofmt -s
- receiver name is inconsistent
- omit unused 2nd value from range
- godoc comment formed incorrectly
- err assigned and not used
- if block ends with a return statement followed by else

tpl/images/images.go

@@ -23,6 +23,7 @@ import (
 	_ "image/jpeg"
 	_ "image/png"
 
+	// Import webp codec
 	_ "golang.org/x/image/webp"
 
 	"github.com/gohugoio/hugo/deps"