### Godot version

4.0.dev (c309de53997feff3286295fb2d71657f112a15db)

### System information

Linux, Nvidia, Vulkan

### Issue description

Editor segfaults when certain conditions are met when using the AnimationPlayer editor.

### Steps to reproduce

1. Create multiple animations, saved into a animation collection
2. Open an existing animation, then make a new empty animation
3. Change from seconds to fps, or add a new property to animate ()
4. Editor crashes

NOTE: It is slightly random and I have not found a perfect repro

### Minimal reproduction project

N/A (TBD?)
ERR_FAIL_COND(p_event.is_null());
	if (panner->gui_input(p_event)) {
		accept_event();
		return;
	}
	const Ref<InputEventMouseButton> mb = p_event;
	if (mb.is_valid() && mb->is_pressed() && mb->is_alt_pressed() && mb->get_button_index() == MouseButton::WHEEL_UP) {
		if (track_edit) {
			track_edit->get_editor()->goto_prev_step(true);
		}
		accept_event();
	}
	if (mb.is_valid() && mb->is_pressed() && mb->is_alt_pressed() && mb->get_button_index() == MouseButton::WHEEL_DOWN) {
		if (track_edit) {
			track_edit->get_editor()->goto_next_step(true);
		}
		accept_event();
	}
	if (mb.is_valid() && mb->is_pressed() && mb->get_button_index() == MouseButton::LEFT && hsize_rect.has_point(mb->get_position())) {
		dragging_hsize = true;
		dragging_hsize_from = mb->get_position().x;
		dragging_hsize_at = name_limit;
	}
	if (mb.is_valid() && !mb->is_pressed() && mb->get_button_index() == MouseButton::LEFT && dragging_hsize) {