Editor crash after playing animation

[qarmin]

Godot version:
3.1 c21ca98

OS/device including version:
Windows 10

Issue description:
I just play animation and this backtrace was shown:

[0] CowData<AnimationPlayer::TrackNodeCache *>::get (c:\pr\godot\core\cowdata.h:151)
[1] Vector<AnimationPlayer::TrackNodeCache *>::operator[] (c:\pr\godot\core\vector.h:85)
[2] AnimationPlayer::_animation_process_animation (c:\pr\godot\scene\animation\animation_player.cpp:347)
[3] AnimationPlayer::_animation_process_data (c:\pr\godot\scene\animation\animation_player.cpp:798)
[4] AnimationPlayer::_animation_process2 (c:\pr\godot\scene\animation\animation_player.cpp:806)
[5] AnimationPlayer::_animation_process (c:\pr\godot\scene\animation\animation_player.cpp:919)
[6] AnimationPlayer::_notification (c:\pr\godot\scene\animation\animation_player.cpp:204)
[7] AnimationPlayer::_notificationv (c:\pr\godot\scene\animation\animation_player.h:61)
[8] Object::notification (c:\pr\godot\core\object.cpp:957)
[9] SceneTree::_notify_group_pause (c:\pr\godot\scene\main\scene_tree.cpp:971)
[10] SceneTree::idle (c:\pr\godot\scene\main\scene_tree.cpp:517)
[11] Main::iteration (c:\pr\godot\main\main.cpp:1877)
[12] OS_Windows::run (c:\pr\godot\platform\windows\os_windows.cpp:2780)
[13] widechar_main (c:\pr\godot\platform\windows\godot_win.cpp:150)
[14] _main (c:\pr\godot\platform\windows\godot_win.cpp:172)
[15] main (c:\pr\godot\platform\windows\godot_win.cpp:184)
[16] __scrt_common_main_seh (d:\agent\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288)
[17] BaseThreadInitThunk

Steps to reproduce:
https://streamable.com/wao5f

Project
AFF.zip