Fix a few notices

lib/ui/tiles/accepted_friend_tile.dart

@@ -30,12 +30,7 @@ class AcceptedFriendTile extends StatelessWidget {
     required this.onRequestDelete,
     required this.onSetFollowing,
     required this.onOpenPrivateConversation,
-  })  : assert(friend != null),
-        assert(user != null),
-        assert(onRequestDelete != null),
-        assert(onSetFollowing != null),
-        assert(onOpenPrivateConversation != null),
-        super(key: key);
+  }) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
@@ -55,32 +50,32 @@ class AcceptedFriendTile extends StatelessWidget {
             ),
       trailing: PopupMenuButton<_FriendMenuChoices>(
         itemBuilder: (c) => [
-              //Open a private conversation
-              PopupMenuItem(
-                child: Text(tr("Private conversation")!),
-                value: _FriendMenuChoices.PRIVATE_CONVERSATION,
-              ),
+          //Open a private conversation
+          PopupMenuItem(
+            child: Text(tr("Private conversation")!),
+            value: _FriendMenuChoices.PRIVATE_CONVERSATION,
+          ),
 
-              // Update following status
-              PopupMenuItem(
-                child: Row(
-                  children: <Widget>[
-                    Icon(friend.following
-                        ? Icons.check_box
-                        : Icons.check_box_outline_blank),
-                    Container(width: 10.0),
-                    Text(friend.following ? tr("Following")! : tr("Follow")!),
-                  ],
-                ),
-                value: _FriendMenuChoices.TOGGLE_FOLLOWING,
-              ),
+          // Update following status
+          PopupMenuItem(
+            child: Row(
+              children: <Widget>[
+                Icon(friend.following
+                    ? Icons.check_box
+                    : Icons.check_box_outline_blank),
+                Container(width: 10.0),
+                Text(friend.following ? tr("Following")! : tr("Follow")!),
+              ],
+            ),
+            value: _FriendMenuChoices.TOGGLE_FOLLOWING,
+          ),
 
-              // Remove the friend from the list
-              PopupMenuItem(
-                child: Text(tr("Remove")!),
-                value: _FriendMenuChoices.REMOVE,
-              ),
-            ],
+          // Remove the friend from the list
+          PopupMenuItem(
+            child: Text(tr("Remove")!),
+            value: _FriendMenuChoices.REMOVE,
+          ),
+        ],
         onSelected: _selectedMenuOption,
       ),
     );

lib/ui/tiles/comment_tile.dart

@@ -27,11 +27,7 @@ class CommentTile extends StatelessWidget {
     required this.user,
     required this.onUpdateComment,
     required this.onDeleteComment,
-  })  : assert(comment != null),
-        assert(user != null),
-        assert(onUpdateComment != null),
-        assert(onDeleteComment != null),
-        super(key: key);
+  }) : super(key: key);
 
   @override
   Widget build(BuildContext context) {

lib/ui/tiles/conversation_message_tile.dart

@@ -37,12 +37,7 @@ class ConversationMessageTile extends StatelessWidget {
     required this.onRequestMessageStats,
     required this.onRequestMessageUpdate,
     required this.onRequestMessageDelete,
-  })  : assert(message != null),
-        assert(user != null),
-        assert(onRequestMessageStats != null),
-        assert(onRequestMessageUpdate != null),
-        assert(onRequestMessageDelete != null),
-        super(key: key);
+  }) : super(key: key);
 
   @override
   Widget build(BuildContext context) => Column(
@@ -83,7 +78,7 @@ class ConversationMessageTile extends StatelessWidget {
                         // Update message content
                         PopupMenuItem(
                           enabled: message.isOwner &&
-                              message.message != null &&
+                              !message.message.isNull &&
                               message.message.content!.isNotEmpty,
                           value: _MenuChoices.REQUEST_UPDATE_CONTENT,
                           child: Text(tr("Update")!),

lib/ui/tiles/conversation_tile.dart

@@ -36,12 +36,7 @@ class ConversationTile extends StatelessWidget {
     required this.onOpen,
     required this.onRequestUpdate,
     required this.onRequestLeave,
-  })  : assert(conversation != null),
-        assert(usersList != null),
-        assert(onOpen != null),
-        assert(onRequestUpdate != null),
-        assert(onRequestLeave != null),
-        super(key: key);
+  })  : super(key: key);
 
   _buildSubInformation(IconData icon, String content) {
     return Row(

lib/ui/tiles/pending_friend_tile.dart

@@ -20,10 +20,7 @@ class PendingFriendTile extends StatelessWidget {
       required this.friend,
       required this.user,
       required this.onRespond})
-      : assert(friend != null),
-        assert(user != null),
-        assert(onRespond != null),
-        super(key: key);
+      : super(key: key);
 
   @override
   Widget build(BuildContext context) {

lib/ui/tiles/post_tile.dart

@@ -59,13 +59,7 @@ class PostTile extends StatefulWidget {
     required this.showPostTarget,
     required this.groupsInfo,
     required this.userNamesClickable,
-  })  : assert(post != null),
-        assert(usersInfo != null),
-        assert(onDeletedPost != null),
-        assert(showPostTarget != null),
-        assert(groupsInfo != null),
-        assert(userNamesClickable != null),
-        super(key: key);
+  }) : super(key: key);
 
   @override
   State<StatefulWidget> createState() => _PostTileState();
@@ -515,7 +509,7 @@ class _PostTileState extends State<PostTile> {
         postID: widget.post.id,
         content: _commentController.text,
         image: _commentImage,
-      )) ;
+      ));
 
       _sendingComment = false;
 
@@ -578,7 +572,7 @@ class _PostTileState extends State<PostTile> {
       isGroup: widget.post.isGroupPost,
     );
 
-    if (newLevel == null || newLevel == widget.post.visibilityLevel) return;
+    if (newLevel == widget.post.visibilityLevel) return;
 
     // Update post visibility
     if (!await _postsHelper.setVisibility(widget.post.id, newLevel)) {

lib/ui/tiles/post_visibility_level_tile.dart

@@ -17,11 +17,7 @@ class PostVisibilityLevelTile extends StatelessWidget {
     required this.title,
     required this.onSelect,
     this.visible = true,
-  })  : assert(level != null),
-        assert(title != null),
-        assert(onSelect != null),
-        assert(visible != null),
-        super(key: key);
+  })  : super(key: key);
 
   @override
   Widget build(BuildContext context) {

lib/ui/tiles/server_conversation_message_tile.dart

@@ -14,9 +14,7 @@ class ServerConversationMessageTile extends StatelessWidget {
     Key? key,
     required this.message,
     required this.users,
-  })  : assert(message != null),
-        assert(users != null),
-        super(key: key);
+  }) : super(key: key);
 
   @override
   Widget build(BuildContext context) {

lib/ui/tiles/simple_user_tile.dart

@@ -22,8 +22,7 @@ class SimpleUserTile extends StatelessWidget {
     this.onTap,
     this.trailing,
     this.subtitle,
-  })  : assert(user != null),
-        super(key: key);
+  })  : super(key: key);
 
   @override
   Widget build(BuildContext context) {