avatar: Show placeholder on image load error.

Previously, if an avatar image failed to load from its URL, the space for the avatar would simply be empty. This could be confusing for the user.

This change adds an errorBuilder to the RealmContentNetworkImage widget. Now, in case of a network error or an invalid URL, a standard placeholder with a person icon is displayed. This provides a better and more consistent user experience.

Fixes #1558.

Author: vinodsingh-dev-gsoc

lib/widgets/user.dart

@@ -90,6 +90,9 @@ class AvatarImage extends StatelessWidget {
       avatarUrl.get(physicalSize),
       filterQuality: FilterQuality.medium,
       fit: BoxFit.cover,
+      errorBuilder: (context, error, stackTrace) {
+        return _AvatarPlaceholder(size: size);
+      },
     );
   }
 }