fix: Prevent controller crashes and memory leaks in game list grid view

- Fix memory leak in PopulateGridView() and FilterGridView() by properly
  deleting old QStandardItemModel instances before creating new ones
- Add safety checks in controller navigation to prevent crashes when
  accessing uninitialized controller data
- Improve controller input handling to only send events to visible and
  properly initialized views
- Add null pointer checks in SetViewMode() to prevent crashes when
  setting current index on empty models
- Add proper cleanup in GameList destructor to prevent memory leaks
  on application shutdown

The main issue was that switching between list and grid views created
new models without properly cleaning up old ones, leading to memory
leaks. Additionally, controller navigation would send keyboard events
to both views simultaneously, causing crashes when one view was not
properly initialized or visible.

Fixes crashes when using controller navigation in grid view mode.

Thanks to Beta Testers acarajé & Hayate Yoshida (吉田 疾風) for finding the bug.

Signed-off-by: Zephyron <zephyron@citron-emu.org>

src/citron/game_list.cpp

@@ -203,6 +203,13 @@ void GameList::FilterGridView(const QString& filter_text) {
     // Repopulate the grid view with filtered items
     QStandardItemModel* hierarchical_model = item_model;
 
+    // Delete the previous flat model if it exists to prevent memory leaks
+    if (QAbstractItemModel* old_model = list_view->model()) {
+        if (old_model != item_model) {
+            old_model->deleteLater();
+        }
+    }
+
     // Create a new flat model for grid view
     QStandardItemModel* flat_model = new QStandardItemModel(this);
 
@@ -470,9 +477,19 @@ GameList::GameList(FileSys::VirtualFilesystem vfs_, FileSys::ManualContentProvid
                 if (!this->isActiveWindow()) {
                     return;
                 }
+
+                // Only send events to visible and properly initialized views
                 QKeyEvent* event = new QKeyEvent(QEvent::KeyPress, key, Qt::NoModifier);
-                QCoreApplication::postEvent(tree_view, event);
+
-                QCoreApplication::postEvent(list_view, event);
+                if (tree_view->isVisible() && tree_view->model()) {
+                    QCoreApplication::postEvent(tree_view, event);
+                }
+
+                if (list_view->isVisible() && list_view->model()) {
+                    // Create a new event for the list view to avoid double deletion
+                    QKeyEvent* list_event = new QKeyEvent(QEvent::KeyPress, key, Qt::NoModifier);
+                    QCoreApplication::postEvent(list_view, list_event);
+                }
             });
 
     // We must register all custom types with the Qt Automoc system so that we are able to use
@@ -496,6 +513,13 @@ void GameList::UnloadController() {
 
 GameList::~GameList() {
     UnloadController();
+
+    // Clean up any custom models that might have been created for grid view
+    if (QAbstractItemModel* current_model = list_view->model()) {
+        if (current_model != item_model) {
+            current_model->deleteLater();
+        }
+    }
 }
 
 void GameList::SetFilterFocus() {
@@ -1114,12 +1138,18 @@ void GameList::SetViewMode(bool grid_view) {
         PopulateGridView();
         tree_view->setVisible(false);
         list_view->setVisible(true);
-        list_view->setCurrentIndex(list_view->model()->index(0, 0));
+        // Only set current index if the model has items
+        if (list_view->model() && list_view->model()->rowCount() > 0) {
+            list_view->setCurrentIndex(list_view->model()->index(0, 0));
+        }
     } else {
         // Restore the hierarchical model for tree view
         list_view->setVisible(false);
         tree_view->setVisible(true);
-        tree_view->setCurrentIndex(item_model->index(0, 0));
+        // Only set current index if the model has items
+        if (item_model && item_model->rowCount() > 0) {
+            tree_view->setCurrentIndex(item_model->index(0, 0));
+        }
     }
 }
 
@@ -1127,6 +1157,13 @@ void GameList::PopulateGridView() {
     // Store the current hierarchical model
     QStandardItemModel* hierarchical_model = item_model;
 
+    // Delete the previous flat model if it exists to prevent memory leaks
+    if (QAbstractItemModel* old_model = list_view->model()) {
+        if (old_model != item_model) {
+            old_model->deleteLater();
+        }
+    }
+
     // Create a new flat model for grid view
     QStandardItemModel* flat_model = new QStandardItemModel(this);
 

src/citron/util/controller_navigation.cpp

@@ -1,4 +1,5 @@
 // SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
+// SPDX-FileCopyrightText: Copyright 2025 Citron Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include "common/settings_input.h"
@@ -42,6 +43,12 @@ void ControllerNavigation::ControllerUpdateEvent(Core::HID::ControllerTriggerTyp
     if (!Settings::values.controller_navigation) {
         return;
     }
+
+    // Safety check: ensure controllers are properly initialized
+    if (!is_controller_set || !player1_controller || !handheld_controller) {
+        return;
+    }
+
     if (type == Core::HID::ControllerTriggerType::Button) {
         ControllerUpdateButton();
         return;
@@ -54,6 +61,11 @@ void ControllerNavigation::ControllerUpdateEvent(Core::HID::ControllerTriggerTyp
 }
 
 void ControllerNavigation::ControllerUpdateButton() {
+    // Safety check: ensure controllers are properly initialized
+    if (!is_controller_set || !player1_controller || !handheld_controller) {
+        return;
+    }
+
     const auto controller_type = player1_controller->GetNpadStyleIndex();
     const auto& player1_buttons = player1_controller->GetButtonsValues();
     const auto& handheld_buttons = handheld_controller->GetButtonsValues();
@@ -91,6 +103,11 @@ void ControllerNavigation::ControllerUpdateButton() {
 }
 
 void ControllerNavigation::ControllerUpdateStick() {
+    // Safety check: ensure controllers are properly initialized
+    if (!is_controller_set || !player1_controller || !handheld_controller) {
+        return;
+    }
+
     const auto controller_type = player1_controller->GetNpadStyleIndex();
     const auto& player1_sticks = player1_controller->GetSticksValues();
     const auto& handheld_sticks = player1_controller->GetSticksValues();