### 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?)
main_panel = memnew(PanelContainer);
	main_panel->set_focus_mode(FOCUS_ALL); 
	add_child(main_panel);
	main_panel->set_v_size_flags(SIZE_EXPAND_FILL);
	HBoxContainer *timeline_scroll = memnew(HBoxContainer);
	main_panel->add_child(timeline_scroll);
	timeline_scroll->set_v_size_flags(SIZE_EXPAND_FILL);
	VBoxContainer *timeline_vbox = memnew(VBoxContainer);
	timeline_scroll->add_child(timeline_vbox);
	timeline_vbox->set_v_size_flags(SIZE_EXPAND_FILL);
	timeline_vbox->set_h_size_flags(SIZE_EXPAND_FILL);
	timeline_vbox->add_theme_constant_override("separation", 0);
	info_message = memnew(Label);
	info_message->set_text(TTR("Select an AnimationPlayer node to create and edit animations."));
	info_message->set_vertical_alignment(VERTICAL_ALIGNMENT_CENTER);
	info_message->set_horizontal_alignment(HORIZONTAL_ALIGNMENT_CENTER);