correctly detect empty lines

cmd/liber/liber.go

@@ -44,7 +44,7 @@ func promptUserStdin(path string, choices []*liber.Metadata) (*liber.Metadata, e
 		fmt.Printf(prompt)
 		os.Stdout.Sync()
 		result, err := rdr.ReadString('\n')
-		if err != nil || result == "" {
+		if err != nil || result == "\n" {
 			break
 		}
 		idx, err := strconv.Atoi(strings.TrimSpace(result))