AudioStreamPlayback method _stop() is not called when AudioStreamPlayer.stop() is called

[fediazc]

Tested versions

4.2.2.stable, 4.3.stable, 4.4.dev2

System information

Godot v4.3.stable - Windows 10.0.19045

Issue description

When calling AudioStreamPlayer.stop(), the corresponding AudioStreamPlayback's _stop() method is not called. The documentation for AudioStreamPlayback._stop() says it should get called in this case.

Steps to reproduce

1. Create a script that extends AudioStreamPlayback, and override the _start() and _stop() methods.
2. Create script that extends AudioStream and a corresponding AudioStream resource that uses this script. Override the AudioStream._instantiate_playback() method, and return a reference to an AudioStreamPlayback child object from the previous step.
3. Create a new scene with an AudioStreamPlayer node. Set its stream property to the AudioStream resource from the previous step. Add a script to the node and call the play() method, followed by a call to the stop() method. Run the project and note that AudioStreamPlayback._stop() is not called.

Minimal reproduction project (MRP)

playback-stop-mrp.zip

When you run the project, observe that the print statement in AudioStreamPlaybackChild._stop() is not executed.

[SourceOfHTML]

Working on this right now, so far all I've got is information, nothing actionable yet, although I'll keep it updated.

[SourceOfHTML]

This problem got hands.

What I've got is that the source thinks that _instantiate_playback() isn't defined. Why it still calls play and not stop, I have yet to figure out.

[SourceOfHTML]

Adding a single line into AudioServer::stop_playback_stream(p_playback) seems to have fixed the issue, though to avoid possibly breaking other things, I'm not gonna PR it yet.