Tweak UserAvatar UI

lib/ui/sharing/user_avator_widget.dart

@@ -23,7 +23,7 @@ class UserAvatarWidget extends StatelessWidget {
     final enteTextTheme = getEnteTextTheme(context);
     final colorScheme = getEnteColorScheme(context);
     final displayChar = (user.name == null || user.name!.isEmpty)
-        ? user.email.substring(0, 1)
+        ? ((user.email?.isEmpty ?? true) ? " " : user.email.substring(0, 1))
         : user.name!.substring(0, 1);
     final randomColor = colorScheme.avatarColors[
         (user.id ?? 0).remainder(colorScheme.avatarColors.length)];
@@ -36,7 +36,7 @@ class UserAvatarWidget extends StatelessWidget {
     return Container(
       height: size,
       width: size,
-      padding: const EdgeInsets.all(4),
+      padding: const EdgeInsets.all(2),
       decoration: BoxDecoration(
         shape: BoxShape.circle,
         color: decorationColor,