add debounce in searchQuery

example/lib/main.dart

@@ -10,6 +10,7 @@ import 'package:stream_chat_flutter/stream_chat_flutter.dart';
 import 'chips_input_text_field.dart';
 import 'notifications_service.dart';
 import 'neumorphic_button.dart';
+import 'dart:async';
 
 void main() async {
   WidgetsFlutterBinding.ensureInitialized();
@@ -284,11 +285,17 @@ class _NewChatScreenState extends State<NewChatScreen> {
 
   Channel channel;
 
+  Timer _debounce;
+
   void _userNameListener() {
+    if (_debounce?.isActive ?? false) _debounce.cancel();
+    _debounce = Timer(const Duration(milliseconds: 500), () {
+      if (mounted)
         setState(() {
           _userNameQuery = _controller.text;
           _isSearchActive = _userNameQuery.isNotEmpty;
         });
+    });
   }
 
   @override
@@ -533,11 +540,17 @@ class _NewGroupChatScreenState extends State<NewGroupChatScreen> {
 
   bool _isSearchActive = false;
 
+  Timer _debounce;
+
   void _userNameListener() {
+    if (_debounce?.isActive ?? false) _debounce.cancel();
+    _debounce = Timer(const Duration(milliseconds: 500), () {
+      if (mounted)
         setState(() {
           _userNameQuery = _controller.text;
           _isSearchActive = _userNameQuery.isNotEmpty;
         });
+    });
   }
 
   @override