No need to defer closing of file.

sizer/main.go

@@ -103,7 +103,6 @@ func IdentifyType(path string) (int, int64, error) {
 func ls(path string) ([]string, error) {
 	var content []string
 	f, err := os.Open(path)
-	defer f.Close()
 	if err != nil {
 		return []string{}, err
 	}