Leaving `BaseButton.shortcut_feedback` enabled raises errors when a button is removed from the scene tree

[rblopes]

Godot version

v4.2.beta2.official [f8818f8]

System information

Godot v4.2.beta2 - KDE neon 5.27 22.04 - X11 - Vulkan (Forward+) - integrated AMD Radeon Vega 11 Graphics (RADV RAVEN) () - AMD Ryzen 5 3400G with Radeon Vega Graphics (8 Threads)

Issue description

Using a button with a shortcut resource and shortcut_feedback set to true raises errors in the debug console if the node is being removed from the scene tree.

I'm attaching a project reproducing the error that uses SceneTree.change_scene_to_file() to trigger the issue.

The following line shows up in the debugger when you hit Enter:

E 0:00:01:0012   start: Timer was not added to the SceneTree. Either add it or set autostart to true.
  <C++ Error>    Condition "!is_inside_tree()" is true.
  <C++ Source>   scene/main/timer.cpp:109 @ start()

Looking through Godot's source code, BaseButton::shortcut_input instantiates a Timer node that is started, but the condition to determine if the button node is leaving the tree is not checked:

// void BaseButton::shortcut_input(const Ref<InputEvent> &p_event) {
if (shortcut_feedback) {
    if (shortcut_feedback_timer == nullptr) {
        shortcut_feedback_timer = memnew(Timer);
        shortcut_feedback_timer->set_one_shot(true);
        add_child(shortcut_feedback_timer);
        shortcut_feedback_timer->set_wait_time(GLOBAL_GET("gui/timers/button_shortcut_feedback_highlight_time"));
        shortcut_feedback_timer->connect("timeout", callable_mp(this, &BaseButton::_shortcut_feedback_timeout));
    }
    
    in_shortcut_feedback = true;
    shortcut_feedback_timer->start();
}

Leaving shortcut_feedback unchecked solves the issue.

Testing the project under Godot 4.0 and 4.1 raises no errors.

Steps to reproduce

• Add a button node to a scene
• Add a shortcut resource to it (be sure shortcut_feedback is enabled)
• Have the user interact with the button by its shortcut
• Use remove_child to remove the button node after button is pressed

Minimal reproduction project

button-shortcut-feedback-bug.zip

[jsjtxietian]

When press Enter, NOTIFICATION_EXIT_TREE arrives earlier than call_shortcut_input, so the timer started after the node left tree and thus caused this bug.