fix(ui): handle empty channel name in StreamChannelAvatar (#2487)

Co-authored-by: xsahil03x <25670178+xsahil03x@users.noreply.github.com>
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Sahil Kumar <xdsahil@gmail.com>

Author: Copilot

packages/stream_chat_flutter/CHANGELOG.md

@@ -1,3 +1,9 @@
+## Upcoming
+
+🐞 Fixed
+
+- Fixed `StreamChannelAvatar` crashing with `RangeError` when user/channel name is empty.
+
 ## 9.22.0
 
 ✅ Added

packages/stream_chat_flutter/lib/src/channel/stream_channel_avatar.dart

@@ -108,7 +108,7 @@ class StreamChannelAvatar extends StatelessWidget {
 
     final fallbackWidget = Center(
       child: Text(
-        channel.name?[0] ?? '',
+        channel.name?.characters.firstOrNull ?? '',
         style: TextStyle(
           color: colorTheme.barsBg,
           fontWeight: FontWeight.bold,