🐛 Fix local db old data cause crash

lib/widgets/attachments/attachment_list.dart

@@ -72,6 +72,7 @@ class _AttachmentListState extends State<AttachmentList> {
     double? consistentValue;
     int portrait = 0, square = 0, landscape = 0;
     for (var entry in _attachmentsMeta) {
+      if (entry == null) continue;
       if (entry!.metadata?['ratio'] != null) {
         if (entry.metadata?['ratio'] is int) {
           consistentValue ??= entry.metadata?['ratio'].toDouble();

lib/widgets/chat/chat_event.dart

@@ -39,7 +39,7 @@ class ChatEvent extends StatelessWidget {
 
   Widget _buildAttachment(BuildContext context, {bool isMinimal = false}) {
     final attachments = item.body['attachments'] != null
-        ? List<String>.from(item.body['attachments'].map((x) => x))
+        ? List<String>.from(item.body['attachments']?.whereType<String>())
         : List<String>.empty();
 
     if (attachments.isEmpty) return const SizedBox();

lib/widgets/posts/post_item.dart

@@ -293,7 +293,7 @@ class _PostItemState extends State<PostItem> {
   @override
   Widget build(BuildContext context) {
     final List<String> attachments = item.body['attachments'] is List
-        ? item.body['attachments']?.cast<String>()
+        ? List.from(item.body['attachments']?.whereType<String>())
         : List.empty();
     final hasAttachment = attachments.isNotEmpty;