fix go linter errors

flint/builtins/builtins.go

@@ -13,9 +13,3 @@ func New(id, level, desc string) BuiltIns {
 		Description: desc,
 	}
 }
-
-func (b BuiltIns) Reset(id, level, desc string) {
-	b.ID = id
-	b.Level = level
-	b.Description = desc
-}

flint/builtins/required.go

@@ -24,16 +24,12 @@ func (b BuiltIns) Required(fm frontmatter.FrontMatter, keys *set.Set[string]) er
 	missing := fmKeys.Missing(keys)
 
 	if missing.Len() > 0 {
-		var errors []string
-		for _, key := range missing.Slice() {
-			errors = append(errors, key)
-		}
 
 		return ErrorKeysRequired{
 			ID:          b.ID,
 			Level:       b.Level,
 			Description: b.Description,
-			Fields:      errors,
+			Fields:      missing.Slice(),
 		}
 	}
 

pkgs/frontmatter/frontmatter.go

@@ -14,6 +14,11 @@ var (
 	ErrNoFrontMatter = errors.New("no front matter found")
 )
 
+var (
+	YAMLSeparator = []byte("---")
+	NewLine       = []byte("\n")
+)
+
 type FrontMatter struct {
 	content []byte
 	data    map[string]interface{}