skip Files without Id; sort Files by Id

tree.go

@@ -3,6 +3,7 @@ package zord_tree
 import (
 	"bufio"
 	"bytes"
+	"cmp"
 	"crypto/md5"
 	"errors"
 	"fmt"
@@ -13,10 +14,10 @@ import (
 	"path"
 	"path/filepath"
 	"regexp"
+	"slices"
 	"strings"
 
 	abcex "g.arns.lt/zordsdavini/abcex/v4"
-	"golang.org/x/exp/slices"
 )
 
 type Config struct {
@@ -568,7 +569,16 @@ FILE_LOOP:
 		if err != nil {
 			return tree, err
 		}
+		if nextFile.Id == "" {
+			continue
+		}
 		tree.Files = append(tree.Files, nextFile)
+		slices.SortFunc(tree.Files, func(a, b File) int {
+			if len(a.Id) == len(b.Id) {
+				return strings.Compare(a.Id, b.Id)
+			}
+			return cmp.Compare(len(a.Id), len(b.Id))
+		})
 	}
 
 	return tree, nil