Fix OGG Vorbis infinite error spam with corrupt file.

[lawnjelly]

When OGG Vorbis encountered unreadable file, it emitted infinite error spam.
This PR returns the full number of frames in the case of error, to prevent infinite loop.

Fixes #84712

Notes

• Bug occurs because if you return 0 with error, the calling function enters an infinite loop as it keeps trying to read.
• Have fixed all 3 error conditions, even though 1 was active in the issue.
• This same bug may be present on other audio readers.

Discussion

Alternatively we could set an error flag. This PR could potentially spam quite a few errors for each audio tile, but it won't enter an infinite loop. If we used an error flag this could prevent more than one error message.

I'm erring on the side of spamming here for now, unless it causes a problem in the wild, or others prefer the flag approach.

[akien-mga]

Looks good!

This same bug may be present on other audio readers.

I checked the other _mix_internal and _mix_* functions for AudioStreamPlaybackMP3, AudioStreamPlaybackMicrophone, and AudioStreamGenerator, I don't see similar problems with returning 0 that would end in infinite loops.

They do return 0 on !active condition, which OggVorbis also does in its _mix_internal, so I assume this is expected. But OggVorbis is the only one with ERR_FAIL conditions as part of its actual mixing.

[ellenhp]

This makes sense to me I think. Returning zero is fine if playback is not active iirc but otherwise it makes sense to return silence. Honestly I'm really reluctant to review or approve anything that touches the interface between the audio server and the streams because Juan wants to refactor that code and I don't want to do anything that will interfere with those plans. This should be small enough that it won't cause problems in a refactor later but I also thought that about #73162. 😕

[akien-mga]

Thanks!

[DevMimas]

Hello, yes I can confirm the bug in Godot Engine v4.2.1.stable.mono.official. It also occurs for me. Even if you rename a folder in which the video file .OGG is located, there is a crash when reimporting the file. When I deleted the file from the commit, the programme worked again.

Improvement of the text
Unfortunately, the error in the output is meaningless for laymen. I could only find out indirectly that this is related to the OGG file.
Could you please define the error text more clearly?
godotengine/godot-proposals#8808