Crashes / Stopping audio after taking Facetime audio call

[Leandros]

After taking a Facetime Audio call, hanging up and returning to the application, ObjectAL either crashes instantly (with [OALAudioSession sharedInstance].handleInterruptions turned on), or after playing a few effects.

These are the two crashes:

The second crash shows something in our logs, the first doesn't:

2016-02-29 16:25:35.623 i Tesla Tubes[6716:2981241] OAL Error: +[ALWrapper sourcePlay:]: Unknown Internal Error (error code 0xffffffff)
2016-02-29 16:25:35.624 i Tesla Tubes[6716:2981241] OAL Warning: -[OALAudioSession onAudioError:]: Received audio error notification. Resetting audio session.

Both crashes are, weirdly enough, always at calls of objc_msgSend, could that be caused by the fact that I'm not using Objective-C, but Objective-C++?

An interesting, and annoying, side effect is, that after taking a Facetime call, all background audio is gone.
And, even more interesting is, the bug only occurs in debug builds, not release builds.