minor changes

lib/ref/xmp.dart

@@ -6,6 +6,7 @@ class XMP {
   static const Map<String, String> namespaces = {
     'adsml-at': 'AdsML',
     'aux': 'Exif Aux',
+    'avm': 'Astronomy Visualization',
     'Camera': 'Camera',
     'creatorAtom': 'After Effects',
     'crs': 'Camera Raw Settings',

lib/widgets/fullscreen/info/metadata/metadata_section.dart

@@ -128,6 +128,8 @@ class _MetadataSectionSliverState extends State<MetadataSectionSliver> with Auto
   }
 
   Widget _buildDirTile(String title, _MetadataDirectory dir) {
+    if (dir.tags.isEmpty) return SizedBox.shrink();
+
     final dirName = dir.name;
     if (dirName == xmpDirectory) {
       return XmpDirTile(