Destroy the window manager before TwitchIrcServer

TwitchIrcServer contains the channels, and they now live longer than the
windows themselves.

I made it so the dtor of WindowManager *actually* deletes the windows
now - i.e. them and everything in them are destroyed.

src/Application.cpp

@@ -109,6 +109,7 @@ Application::Application(Settings &_settings, Paths &_paths)
     , emotes(&this->emplace<Emotes>())
     , accounts(&this->emplace<AccountController>())
     , hotkeys(&this->emplace<HotkeyController>())
+    , twitch(&this->emplace<TwitchIrcServer>())
     , windows(&this->emplace<WindowManager>())
     , toasts(&this->emplace<Toasts>())
     , imageUploader(&this->emplace<ImageUploader>())
@@ -117,7 +118,6 @@ Application::Application(Settings &_settings, Paths &_paths)
     , commands(&this->emplace<CommandController>())
     , notifications(&this->emplace<NotificationController>())
     , highlights(&this->emplace<HighlightController>())
-    , twitch(&this->emplace<TwitchIrcServer>())
     , chatterinoBadges(&this->emplace<ChatterinoBadges>())
     , ffzBadges(&this->emplace<FfzBadges>())
     , seventvBadges(&this->emplace<SeventvBadges>())

src/Application.hpp

@@ -98,6 +98,7 @@ public:
     Emotes *const emotes{};
     AccountController *const accounts{};
     HotkeyController *const hotkeys{};
+    TwitchIrcServer *const twitch{};
     WindowManager *const windows{};
     Toasts *const toasts{};
     ImageUploader *const imageUploader{};
@@ -106,7 +107,6 @@ public:
     CommandController *const commands{};
     NotificationController *const notifications{};
     HighlightController *const highlights{};
-    TwitchIrcServer *const twitch{};
     ChatterinoBadges *const chatterinoBadges{};
     FfzBadges *const ffzBadges{};
     SeventvBadges *const seventvBadges{};

src/singletons/WindowManager.cpp

@@ -127,7 +127,16 @@ WindowManager::WindowManager()
     });
 }
 
-WindowManager::~WindowManager() = default;
+WindowManager::~WindowManager()
+{
+    for (const auto &window : this->windows_)
+    {
+        // We would prefer to use window->deleteLater() here, but the timings are too tight
+        // Channel's completion model gets destroyed before the deleteLater call actually deletes the
+        // UI objects that rely on the completion model
+        delete window;
+    }
+}
 
 MessageElementFlags WindowManager::getWordFlags()
 {