Mouse: Convert to try_create_default_icon

Author: https://github.com/Astraeus-
Commit: 1adc808664
Pull-request: https://github.com/SerenityOS/serenity/pull/11293

Userland/Demos/Mouse/main.cpp

@@ -160,7 +160,7 @@ private:
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
     auto app = TRY(GUI::Application::try_create(arguments));
-    auto app_icon = GUI::Icon::default_icon("app-mouse");
+    auto app_icon = TRY(GUI::Icon::try_create_default_icon("app-mouse"));
 
     TRY(Core::System::pledge("stdio recvfd sendfd rpath"));
     TRY(Core::System::unveil("/res", "r"));