implemented disposal guard in files search controller to safely handle async listener notifications

lib/view/pages/files/search/files_search_controller.dart

@@ -25,6 +25,16 @@ class FilesSearchController extends ChangeNotifier {
   bool _serverLoading = false;
   Object? _serverError;
   int _serverEpoch = 0;
+  bool _disposed = false;
+
+  /// Guards against the race where the search delegate is closed (and the
+  /// controller disposed) while a debounced cache scan or server call is
+  /// still in flight: their late `notifyListeners()` would otherwise throw
+  /// on a disposed `ChangeNotifier`.
+  void _safeNotify() {
+    if (_disposed) return;
+    _safeNotify();
+  }
 
   String get query => _query;
   List<String> get pathScope => List.unmodifiable(_pathScope);
@@ -60,7 +70,7 @@ class FilesSearchController extends ChangeNotifier {
       _serverResults = const [];
       _serverLoading = false;
       _serverError = null;
-      notifyListeners();
+      _safeNotify();
       return;
     }
     // Show loading immediately — even before the (typically fast) cache
@@ -68,12 +78,12 @@ class FilesSearchController extends ChangeNotifier {
     // starts typing rather than after the first await hop.
     _serverLoading = true;
     _serverError = null;
-    notifyListeners();
+    _safeNotify();
 
     final cacheHits = await searchLocalCaches(_query, pathScope: _pathScope);
     if (epoch != _serverEpoch) return;
     _cacheResults = cacheHits;
-    notifyListeners();
+    _safeNotify();
     _scheduleServerCall();
   }
 
@@ -84,17 +94,17 @@ class FilesSearchController extends ChangeNotifier {
     _pathScope = const [];
     final epoch = ++_serverEpoch;
     if (_query.trim().isEmpty) {
-      notifyListeners();
+      _safeNotify();
       return;
     }
     _serverLoading = true;
     _serverError = null;
-    notifyListeners();
+    _safeNotify();
 
     final cacheHits = await searchLocalCaches(_query);
     if (epoch != _serverEpoch) return;
     _cacheResults = cacheHits;
-    notifyListeners();
+    _safeNotify();
     _scheduleServerCall();
   }
 
@@ -106,7 +116,7 @@ class FilesSearchController extends ChangeNotifier {
     Debouncer.cancel(_debounceTag);
     _serverLoading = true;
     _serverError = null;
-    notifyListeners();
+    _safeNotify();
     _runServerCall();
   }
 
@@ -128,18 +138,19 @@ class FilesSearchController extends ChangeNotifier {
           .toList();
       _serverLoading = false;
       _serverError = null;
-      notifyListeners();
+      _safeNotify();
     } on Object catch (e) {
       if (epoch != _serverEpoch) return;
       _serverResults = const [];
       _serverLoading = false;
       _serverError = e;
-      notifyListeners();
+      _safeNotify();
     }
   }
 
   @override
   void dispose() {
+    _disposed = true;
     Debouncer.cancel(_debounceTag);
     super.dispose();
   }