SpriteFrames window renaming animation to empty still causes error and spurious naming conflict if already "new_animation"

[hsandt]

Godot version

v4.0.rc4.official [e0de357]

System information

Linux Ubuntu 20.04 with Unity desktop

Issue description

Following PR #70788 solving issue #70769, there are still a few bugs remaining.

1. Editing any animation name to empty string will auto-fix it with "new_animation[suffix]" as expected, but still show the Output error just before:

Animation '' doesn't exist.
Rename Animation

2. Renaming an animation already named "new_animation[suffix]" will consider the old name to be reserved, causing a conflict with itself and increment the suffix without needing to. For instance, "new_animation" -> empty string will become "new_animation_1". If "new_animation_1" already exists, it will become "new_animation_2", etc.

Basically, it should behave as if the user actually input "new_animation" instead of empty string. Looking at 6297665 I'd say that the empty -> "new_animation" fallback should be done earlier, before if (new_name == String(edited_anim)) to fix 2. and before if (!frames->has_animation(edited_anim)) to fix 1. But I'm not sure of possible side effects, so this needs to be tested.

Steps to reproduce

1. In any project: create new Sprite Frames resource
2. In SpriteFrames window: you'll see "default" animation. Try to rename it to empty string -> becomes "new_animation" as it should.
3. Check the Output console: observe error "Animation '' doesn't exist."
4. Rename the animation to empty string again. This time, it becomes "new_animation_1".
5. Try various combinations of existing suffixes by adding new animations multiple times, and observe how number resolution by increment occurs as usual, but unnecessarily skipping the very animation that is renamed.

Minimal reproduction project

N/A

[Rindbee]

Whenever an animation is renamed, the following error message is output:

ERROR: Animation '' doesn't exist.
   at: get_frame_count (scene/resources/sprite_frames.cpp:71)

It is mainly caused by the following code:

godot/editor/plugins/sprite_frames_editor_plugin.cpp

Line 958 in 57919be

_rename_node_animation(undo_redo, false, edited_anim, "", "");

godot/editor/plugins/sprite_frames_editor_plugin.cpp

Line 990 in 57919be

undo_redo->add_do_method(E, "set_animation", p_new_animation);

godot/scene/2d/animated_sprite_2d.cpp

Line 531 in 57919be

int frame_count = frames->get_frame_count(animation);